Document:

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                                                                  EXHIBIT (10)-2

                                                                  EXECUTION COPY

                                LEASE AGREEMENT

                                 by and between

                             TRANSCO TOWER LIMITED

                                      and

                   TRANSCONTINENTAL GAS PIPE LINE CORPORATION

                          Dated as of October 23, 2003

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                                TABLE OF CONTENTS

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DEFINITIONS ..................................................................................      1

ARTICLE 1 LEASED PREMISES; TERMINATION RIGHT .................................................      1
  Section 1.01   Leased Premises .............................................................      1
  Section 1.02   Net Rentable Area ...........................................................      1
  Section 1.03   Contraction Option ..........................................................      2
  Section 1.04   Written Confirmation after Contraction ......................................      3
  Section 1.05   AS IS Condition .............................................................      4
  Section 1.06   Termination Right ...........................................................      4
  Section 1.07   Rooftop .....................................................................      4
  Section 1.08   Risers ......................................................................      9

ARTICLE 2 TERM; USE; BASE RENTAL; OPERATING EXPENSES .........................................     10
  Section 2.01   Term ........................................................................     10
  Section 2.02   Use .........................................................................     10
  Section 2.03   Base Rental .................................................................     11
  Section 2.04   Net Lease ...................................................................     12
  Section 2.05   Operating Expenses ..........................................................     12

ARTICLE 3 SERVICES ...........................................................................     21
  Section 3.01   Services to Be Furnished by Landlord ........................................     21
  Section 3.02   Interruption in Essential Services ..........................................     23
  Section 3.03   Keys and Locks ..............................................................     24
  Section 3.04   Graphics ....................................................................     24
  Section 3.05   Peaceful Enjoyment ..........................................................     25
  Section 3.06   Repairs by Landlord .........................................................     25

ARTICLE 4 SERVICES; ASSIGNMENT AND SUBLETTING; ALTERATIONS;
SUBORDINATION; INITIAL IMPROVEMENTS ..........................................................     26
  Section 4.01   Payments by Tenant ..........................................................     26
  Section 4.02   Repairs by Tenant ...........................................................     26
  Section 4.03   Care of Leased Premises .....................................................     26
  Section 4.04   Assignment or Sublease ......................................................     26
  Section 4.05   Alterations .................................................................     32
  Section 4.06   Legal Use and Violations of Insurance Coverage ..............................     36
  Section 4.07   Laws, Regulations and Rules of the Building .................................     37
  Section 4.08   Entry for Repair and Inspection .............................................     38
  Section 4.09   Nuisance ....................................................................     39
  Section 4.10   Subordination to Mortgage; Non-Disturbance ..................................     39
  Section 4.11   Estoppel Certificate ........................................................     41
  Section 4.12   Tenant's Initial Improvements ...............................................     42
  Section 4.13   Liens .......................................................................     42
  Section 4.14   Limitation of Landlord's Personal Liability .................................     42
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  Section 4.15   Parking .....................................................................     43

ARTICLE 5 COVENANTS; MISCELLANEOUS PROVISIONS ................................................     44
  Section 5.01   Condemnation ................................................................     44
  Section 5.02   Damages From Certain Causes .................................................     45
  Section 5.03   Waiver of Landlord's Lien ...................................................     46
  Section 5.04   Landlord's Right to Relet ...................................................     46
  Section 5.05   Holding Over ................................................................     46
  Section 5.06   Fire or Other Casualty Clause ...............................................     47
  Section 5.07   Attorney's Fee ..............................................................     48
  Section 5.08   Amendments ..................................................................     48
  Section 5.09   Assignment by Landlord ......................................................     49
  Section 5.10   Default by Tenant ...........................................................     49
  Section 5.11   Non-Waiver ..................................................................     52
  Section 5.12   Casualty Insurance of Landlord ..............................................     52
  Section 5.13   Tenant's Insurance ..........................................................     53
  Section 5.14   Indemnity; Hold Harmless ....................................................     55
  Section 5.15   Waiver of Subrogation Rights ................................................     57
  Section 5.16   Name of Building ............................................................     57
  Section 5.17   Survival ....................................................................     58
  Section 5.18   Entire Agreement ............................................................     58
  Section 5.19   Time Is of the Essence. .....................................................     58
  Section 5.20   Force Majeure ...............................................................     58
  Section 5.21   Brokers .....................................................................     59
  Section 5.22   No Warranties ...............................................................     59
  Section 5.23   Notices .....................................................................     60
  Section 5.24   Severability ................................................................     60
  Section 5.25   Authority ...................................................................     60
  Section 5.26   Mutual Waivers of Jury Trial and Certain Damages ............................     60
  Section 5.27   Binding Effect ..............................................................     61
  Section 5.28   Cumulative ..................................................................     61

ARTICLE 6 RENEWAL OPTIONS ....................................................................     61
  Section 6.01   Renewal Options; Exercise of Options ........................................     61
  Section 6.02   Terms of Renewal Term .......................................................     63
  Section 6.03   Arbitration .................................................................     65

ARTICLE 7 RIGHT OF FIRST OFFER ...............................................................     66
  Section 7.01   Right of First Offer ........................................................     66
  Section 7.02   Procedure ...................................................................     66
  Section 7.03   Determination of Market Rental ..............................................     67
  Section 7.04   Additional Conditions .......................................................     68
  Section 7.05   Time of the Essence .........................................................     68

ARTICLE 8 RIGHT OF FIRST REFUSAL .............................................................     68
  Section 8.01   Right of First Refusal ......................................................     68
  Section 8.02   Conditions ..................................................................     68
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  Section 8.03   Applicable Terms for Right of First Refusal .................................     68
  Section 8.04   Time of the Essence .........................................................     69

ARTICLE 9 CLUB MEMBERSHIPS ...................................................................     69
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                    LIST OF SCHEDULES AND EXHIBITS

SCHEDULES:

Schedule 1 - Definitions

Schedule 2 - Base Annual Rental

Schedule 3 - Base Rental Credit

Schedule 4 - Tenant's Initial Improvements

Schedule 5 - Approved Rooftop Equipment

Schedule 6 - Base Rooftop Rental

Schedule 7 - Contraction Payment

Schedule 8 - Termination Payment

Schedule 9 - Janitorial Services

EXHIBITS:

Exhibit A - Floor Plan of Leased Premises

Exhibit B - Land Description

Exhibit C - Parking Space Radius

Exhibit D - Roof Space

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                                 LEASE AGREEMENT

      THIS LEASE AGREEMENT (collectively, as may be amended from time-to-time,
this "Lease") is made and entered into as of October 23, 2003, between TRANSCO
TOWER LIMITED, a Texas limited partnership, having an address at 2800 Post Oak
Boulevard, Houston, Texas 77056, (hereinafter called "Landlord"), and
TRANSCONTINENTAL GAS PIPE LINE CORPORATION, a Delaware corporation, having an
address at Williams Tower, 2800 Post Oak Boulevard, Houston Texas 77056
(hereinafter called "Tenant").

                                   DEFINITIONS

      (a) All capitalized terms used in this Lease without definition are
defined in Schedule 1.

      (b) For purposes of this Lease, whenever the words "include", "includes",
or "including" are used, they shall be deemed to be followed by the words
"without being limited to".

                                   ARTICLE 1
                                LEASED PREMISES;
                               TERMINATION RIGHT

      SECTION 1.01 LEASED PREMISES

      Subject to and upon the terms, provisions and conditions hereinafter set
forth, and each in consideration of the duties, covenants and obligations of the
other hereunder, Landlord does hereby lease, demise and let to Tenant and Tenant
does hereby lease and take from Landlord the Leased Premises.

      SECTION 1.02 NET RENTABLE AREA

      The term "Net Rentable Area", as used herein, shall refer to (i) in the
case of a single tenant floor, all floor area measured from the inside surface
of the inner glass or (with respect to the basements) interior wall of the
Building to the inside surface of the opposite outer wall excluding only the
areas ("service areas") within the outside walls on the particular floor used
for building stairs, fire towers, elevator shafts, flues, vents, stacks,
vertical pipe shafts and vertical ducts, but including any such service areas
which are for the specific use of the particular tenant such as special stairs
or elevators, plus a proportionate part of the areas ("extra areas") used for
building elevator, mechanical, electrical and plumbing rooms and the central
plant serving the Building, the truck dock, the bridge connecting the Building
with the Garage, fire control stations, and ground floor, basement, second floor
and 51st floor lobbies, and (ii) in the case of a floor to be occupied by more
than one tenant, all floor areas within the demising walls (measured from the
mid-point of the demising walls and in the case of exterior walls, measured as
defined

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in (i) above), plus a proportionate part of areas ("common areas") devoted to
lobbies, corridors, elevator foyers, rest rooms, electrical, telephone and
mechanical rooms, janitor closets, vending areas and other similar facilities
for the use of all tenants on the particular floor plus a proportionate part of
the extra areas. Tenant's proportionate part of extra areas shall be based upon
the ratio of Tenant's Net Rentable Area (excluding extra areas) to the aggregate
Net Rentable Area (excluding extra areas) of the Building. Tenant's
proportionate part of common areas Shall be based upon the ratio of the Tenant's
Net Rentable Area (excluding common areas and extra areas) to the aggregate Net
Rentable Area (excluding common areas and extra areas) on such floor. No
deductions shall be made in determining Net Rentable Area for columns or
projections necessary to the Building. The Net Rentable Area in the Leased
Premises has been calculated on the basis of the foregoing definition and is
hereby stipulated for all purposes hereof to be the Net Rentable Area of the
Leased Premises set forth in Schedule 1, whether the same shall be more or less
as a result of variations resulting from actual construction and completion of
the Leased Premises for occupancy so long as such work is done substantially in
accordance with the terms and provisions hereof.

      SECTION 1.03 CONTRACTION OPTION

            (a) Tenant shall have the right to surrender to Landlord the entire
      17th Level of the Building (such floor being the "Contracted Portion of
      the Leased Premises"), at any time on or after March 30, 2007 (such date
      of surrender being the "Contraction Date") upon irrevocable written notice
      (the "Contraction Notice") of such election delivered to Landlord not less
      than 12 months prior to the Contraction Date together with payment to
      Landlord of the Contraction Payment on or prior to the Contraction Date.
      The occurrence of any of the following shall render the Contraction Notice
      null and void:

                  (i) Tenant's failure to pay the Contraction Payment prior to
            the Contraction Date;

                  (ii) the existence of a Material Event of Default as of the
            delivery date of the Contraction Notice; or

                  (iii) Tenant's failure to deliver to Landlord the Contracted
            Portion of the Leased Premises no later than the Contraction Date.

      (b) The term "Contraction Payment" means the amount determined in
accordance with the formula set forth on Schedule 7.

      (c) In the event Tenant delivers the Contraction Notice in accordance with
the foregoing, Tenant shall surrender possession of the Contracted Portion of
the Leased Premises to Landlord on the Contraction Date. Upon such surrender,
the Contracted Portion of the Leased Premises shall be delivered to Landlord
vacant of Tenant's occupancy, free and clear of all occupancies and tenancies
created by Tenant and all rights of possession of Tenant under this Lease and in
the condition otherwise required under this Lease upon the expiration of the
Term.

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      (d) Provided all other requirements of this Section 1.03 have been
satisfied, the following shall apply effective as of the Contraction Date:

                  (i) Tenant's right to possess the Contracted Portion of the
            Leased Premises for the unexpired Term of this Lease and all of
            Tenant's right, title and interest under this Lease with respect to
            the Contracted Portion of the Leased Premises shall revert to
            Landlord;

                  (ii) the Leased Premises shall be deemed to exclude the
            Contracted Portion of the Leased Premises and Tenant's Share shall
            be recalculated accordingly;

                  (iii) no further payment of any Rent shall become due and
            payable by Tenant under this Lease with respect to the Contracted
            Portion of the Leased Premises for any period after the Contraction
            Date;

                  (iv) no further performance shall be required by Tenant or
            Landlord of any obligation under this Lease with respect to the
            Contracted Portion of the Leased Premises (except to the extent of
            any obligation accruing prior to the Contraction Date); and

                  (v) with respect to the Contracted Portion of the Leased
            Premises, this Lease shall be, to such extent only, deemed complete,
            expired and terminated as of the Contraction Date and commencing as
            of the Contraction Date neither Landlord nor Tenant shall have any
            right or obligation under this Lease with respect to the Contracted
            Portion of the Leased Premises (except to the extent of any
            obligations accruing prior to the Contraction Date).

      SECTION 1.04 WRITTEN CONFIRMATION AFTER CONTRACTION

      (a) At anytime after the Contraction Date, Tenant shall, upon Landlord's
request, execute and deliver a written confirmation setting forth the following
(taking into account the exclusion of the Contracted Portion of the Leased
Premises from the Leased Premises in accordance with Section 1.03):

                  (i) a description of the Leased Premises;

                  (ii) the Net Rentable Area of the Leased Premises;

                  (iii) the Base Rental and the Base Rental Credit (each
            reflected in monthly and annual amounts); and

                  (iv) the Minimum Number of Parking Spaces (reflected in an
            aggregate number rather than the formula set forth in Schedule 1).

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      (b) The failure of Landlord to request such confirmation or Tenant to
execute and deliver such confirmation shall not affect the terms of this Lease.

      SECTION 1.05 AS IS CONDITION

      Landlord shall be deemed to have delivered possession of the Leased
Premises to Tenant as of the Commencement Date. Tenant shall accept the Leased
Premises in its "AS IS" condition and agrees (a) that neither Landlord nor
Landlord's agents have made any representations or warranties with respect to
the Leased Premises or any portion of the Project except as expressly set forth
in this Lease, and (b) except with respect to Landlord's ADA Initial Work,
Landlord shall have no obligation to perform any work, supply any materials,
incur any expense or make any alterations or improvements to the Leased Premises
to prepare the Leased Premises for Tenant's occupancy and possession. Tenant's
occupancy of the Leased Premises as currently demised to Tenant under the Lease
Agreement, dated October 5, 1981 (as amended, the "1981 Lease") shall be deemed
conclusive evidence, as against Tenant, that Tenant has accepted the Leased
Premises in its then current condition and that the Leased Premises and the
Building were in a good and satisfactory condition as required by this Lease.

      SECTION 1.06 TERMINATION RIGHT

            (a) Tenant shall have the right to terminate this Lease, upon
      irrevocable written notice ("Tenant's Termination Notice") to Landlord of
      such election delivered not later than March 29, 2008 (TIME SHALL BE OF
      THE ESSENCE WITH RESPECT TO SUCH DATE). If Tenant fails to deliver
      Tenant's Termination Notice to Landlord on or prior to March 29, 2008,
      Tenant's right to terminate pursuant to this Section 1.06 shall lapse and
      Tenant shall have no further right to terminate this Lease.

      (b) The term "Termination Payment" means the amount determined in
accordance with the formula set forth on Schedule 8.

      (c) In the event Tenant elects to terminate this Lease in accordance with
the terms of Section 1.06(a), (i) Tenant shall pay (x) one half (1/2) of the
Termination Payment on or prior to March 29, 2008 and (y) the remainder of the
Termination Payment no later than March 29, 2009 (the "Termination Date") (TIME
SHALL BE OF THE ESSENCE WITH RESPECT TO EACH OF SUCH DATES) and (ii) this Lease
shall terminate and the Term shall come to an end effective as of the
Termination Date. Tenant's failure to pay either portion of the Termination
Payment in accordance with the terms hereof shall render such notice null and
void.

      SECTION 1.07 ROOFTOP

      (a) Tenant shall be permitted to use the Roof Space and Rooftop Equipment
Closet for the installation, maintenance and operation of satellite dishes and
related equipment approved by Landlord (collectively, the "Rooftop Equipment")
for use in connection with Tenant's business at the Leased Premises. Landlord
acknowledges that the equipment described on Schedule 5 is hereby approved in
connection with the foregoing. Tenant shall not use the Roof

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Space or the Rooftop Equipment Closet for recreational, commercial (other than
in connection with the conduct of Tenant's business) or promotional purposes. In
addition to Tenant's payment of Base Rental and all other Rent charges required
hereunder, Tenant shall pay (i) Base Rooftop Rental and (ii) for all electric
service required to operate all of its equipment on the Roof Space and in the
Rooftop Equipment Closet, in accordance with the terms of Section
l.07(c)(viii)). Tenant shall pay to Landlord Base Rooftop Rental for use of the
Roof Space. Tenant shall pay the Base Rooftop Rental in equal monthly,
installments, in advance, on or before the first (1st) day of each calendar
month during the Term, commencing on the Commencement Date.

            (b) (i) Subject to Landlord's approval, Tenant may install, and once
            installed modify, the Rooftop Equipment on the Roof Space or in the
            Rooftop Equipment Closet for use in connection with Tenant's
            business in the Leased Premises. Before commencing installation of
            such equipment on the Roof Space, Tenant shall furnish detailed
            plans and specifications for such systems (or modifications thereto)
            to Landlord for Landlord's prior written approval. Upon approval,
            such Rooftop Equipment shall be installed, at Tenant's expense, by a
            contractor selected by Tenant and approved by Landlord (such
            approval to be in Landlord's sole discretion). The installation of
            the Rooftop Equipment shall include the reasonable use of any
            Building shafts and risers required to bring Tenant's electrical
            wiring, airways and pipes from the Leased Premises to the Roof Space
            or the Rooftop Equipment Closet (as applicable). To the extent that
            the Roof Space or the Rooftop Equipment Closet is damaged by the
            installation, maintenance, operation, repair or removal of the
            Rooftop Equipment, Tenant shall promptly repair such damage. Tenant
            shall be responsible for procuring all licenses or permits required
            for the installation or use of the Rooftop Equipment or operation of
            any equipment served thereby, and Landlord makes no warranties
            whatsoever as to the permissibility of such systems under any Legal
            Requirement. Tenant shall comply with all applicable roof warranties
            in respect to Tenant's activities on the Roof Space (provided
            Landlord has provided Tenant with notice of such warranties and the
            requirements thereof).

                  (ii) Tenant's Rooftop Equipment shall not be permitted to
            constitute a nuisance or unreasonably interfere with the normal use
            of any portion of the Building or the area surrounding the Building
            by occupants thereof. Subject to Sections 1.07(c)(ii) and (c)(iii)
            below, in the event that Tenant's Rooftop Equipment and other
            rooftop equipment to be installed by another tenant or occupant of
            the Building interfere with one another or are otherwise unsuitable
            for simultaneous use, Tenant's Rooftop Equipment shall be given
            priority Landlord acknowledges that to its actual knowledge, without
            inquiry, as of the date hereof any existing Rooftop Equipment
            installed by Tenant prior to the date hereof does not interfere with
            the rooftop equipment installed by any other tenant prior to the
            date hereof.

            (c) (i) The size and dimensions of the Rooftop Equipment, as well as
            the location of such equipment within the Roof Space or the Rooftop
            Equipment

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            Closet (as applicable) for such installation, shall be subject to
            Landlord's prior approval.

                  (ii) The installation and position of the Rooftop Equipment
            shall comply with all applicable Legal Requirements. To the extent
            necessary to comply with applicable Legal Requirements, Landlord (at
            no cost to Landlord) shall join in all applications for any license,
            permit or other filing necessary for Tenant's installation or
            operation of the Rooftop Equipment.

                  (iii) The installation of any electrical or communications
            lines ("Wiring") and related equipment in connection with the
            installation and operation of the Rooftop Equipment, as well as the
            manner and location (i.e., routing) of all Wiring and related
            equipment in connection therewith shall be subject to Landlord's
            prior approval and shall comply with all applicable Legal
            Requirements.

                  (iv) The Rooftop Equipment, including all Wiring, shall be
            maintained and kept in good repair by Tenant.

                  (v) Tenant shall not install any equipment without (1)
            Landlord's prior approval of the manner of such installation, and
            (2) delivery to and approval by Landlord of the detailed plans and
            specifications specified in Section 1.07(b)(i). Landlord may permit
            the use of any other portion of the roof other than the Roof Space
            by any other Person for any use, including the installation of other
            antenna, Rooftop Equipment and support equipment.

                  (vi) For the purpose of installing, servicing or repairing the
            Rooftop Equipment, Wiring and related equipment, Tenant shall have
            access to the Roof Space and the Rooftop Equipment Closet upon
            reasonable prior notice to Landlord. All access by Tenant to the
            Roof Space, the Rooftop Equipment Closet and other areas of the
            Building shall be subject to Landlord's reasonable safeguards for
            the security and protection of the Building, the Building equipment
            and installations and equipment of other tenants of the Building as
            may be located on the roof of the Building. Landlord shall have the
            right to assign a Building representative to be present during the
            duration of Tenant's exercise of any access to the Roof Space and
            the Rooftop Equipment Closet.

                  (vii) Tenant, at Tenant's expense, shall comply with all
            applicable Legal Requirements relating to Tenant's repair,
            maintenance and operation of the Rooftop Equipment and Wiring
            erected or installed by Tenant pursuant to the provisions of this
            Section. Tenant, at Tenant's expense, shall secure and thereafter
            maintain all permits and licenses required for the installation and
            operation of the Rooftop Equipment and all Wiring erected or
            installed by Tenant

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            pursuant to the provisions of this Section, including any approval,
            license or permit required from the Federal Communications
            Commission.

                  (viii) Tenant shall pay, as Additional Rent, for all
            electrical service required for Tenant's use of the Rooftop
            Equipment erected or installed by Tenant pursuant to the provisions
            of this Section. Such electric service shall feed off the supply of
            electrical energy furnished to the Leased Premises. Unless otherwise
            provided in this Lease, the charges for such electrical service
            shall be equal to Landlord's Actual Cost of the same.

                  (ix) Tenant shall be required to remove the Rooftop Equipment
            and all Wiring installed by Tenant, pursuant to the provisions of
            this Section upon the expiration of the Term, or upon its earlier
            termination. Tenant, at Tenant's expense, shall promptly repair any
            and all damages to the Roof Space, the Rooftop Equipment Closet and
            to any other part of the Building caused by or resulting from the
            installation, maintenance and repair, operation or removal of such
            equipment.

                  (x) Notwithstanding anything to the contrary in this Lease and
            unless otherwise expressly provided herein, Landlord shall not he
            required to provide any services whatsoever to the Roof Space or the
            Rooftop Equipment Closet.

                  (xi) All installations made by Tenant on the Roof Space, in
            the Rooftop Equipment Closet or in any other part of the Building
            pursuant to the provisions of this Section shall be at the sole risk
            of Tenant, and neither Landlord nor Landlord's agent or employees
            shall be liable for any damages or injury thereto caused in any
            manner, unless the same shall proximately result from the gross
            negligence or willful conduct of Landlord, its agents and employees.

                  (xii) Tenant will, and does hereby, indemnify and save
            harmless Landlord from and against: (1) any and all claims,
            reasonable counsel fees, demands, damages, expenses or losses by
            reason of any liens, orders, claims or charges resulting from any
            work done, or materials or supplies furnished, in connection with
            the fabrication, erection, installation, maintenance and operation
            of the Rooftop Equipment and any Wiring installed by Tenant pursuant
            to the provisions of this Section except to the extent caused by the
            gross negligence or willful misconduct of Landlord, or its agents or
            employees; and (2) any and all claims, costs, demands, expenses,
            fees or suits arising out of accidents, damage, injury or loss to
            any and all Persons and property, or either, whomsoever or
            whatsoever resulting from or arising in connection with the
            erection, installation, maintenance and operation and repair of the
            Rooftop Equipment and all Wiring installed by Tenant pursuant to the
            provisions of this Section; except to the extent caused by the gross
            negligence of Landlord, or its agents or employees. If any
            installations referred to in this Section should revoke, negate or
            in any manner impair or limit any roof warranty or guaranty obtained
            by Landlord, then Tenant

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            shall reimburse Landlord for any loss or damage sustained or costs
            or expenses incurred by Landlord as a result thereof.

                  (xiii) Tenant agrees that the Rooftop Equipment and all Wiring
            installed by Tenant shall not interfere with or adversely affect any
            equipment, installations, lines or machinery of the Building or any
            other tenant of the Building, including any other communications
            equipment in, on top of or otherwise outside the Building, or access
            thereto for maintenance, repair or removal; provided, however, to
            the extent that Tenant's Rooftop Equipment has priority over rooftop
            equipment or another tenant pursuant to Section 1 .07(b)(ii) above
            any interference under this clause (xiii) shall not be deemed to be
            an interference by Tenant with the equipment of such other tenant.

                  (xiv) Tenant acknowledges being advised by Landlord that
            Landlord has the right to grant to third parties, various rights and
            licenses to utilize various portions of the Building and rooftop
            thereof for the installation of microwave dishes, satellite
            communications equipment, whip antennae and other communications
            equipment and related equipment (hereinafter all of the foregoing
            are collectively referred to as "Other Communications Equipment")
            and that, inasmuch as Landlord's ability to facilitate the
            installation and operation of such Other Communications Equipment
            will be of paramount importance to Landlord, Landlord shall have the
            right, at any time and from time to time, during the Term, upon 30
            days' prior written notice to Tenant, to relocate the Tenant's
            Rooftop Equipment and any Wiring to other areas of the Project, as
            Landlord may reasonably determine so as to accommodate such Other
            Communications Equipment on the roof of the Building and so as to
            eliminate, or not to create, problems of interference with respect
            to or between Other Communications Equipment now, or in the future,
            installed on the roof or other areas of the Building provided,
            however, that (1) such relocations shall be done at Landlord's
            expense, (2) such relocation shall not interfere with Tenant's use
            of the Rooftop Equipment and Wiring or materially limit the
            functionality thereof, (3) Landlord shall indemnify, defend and hold
            harmless Tenant from any and against any and all claims, reasonable
            counsel fees, demands, damages, expenses or losses by reason of the
            exercise of its relocation right or any accidents, damage, injury or
            loss to any and all Persons and property, or either, whomever or
            whatsoever resulting from or arising in connection with the exercise
            by Landlord of its relocation right and (4) Landlord shall comply
            with all applicable Legal Requirements and obtain any necessary
            permits and licenses with respect to the exercise of its relocation
            right and the Rooftop Equipment and any Wiring, as relocated. Such
            relocation shall, to the extent practicable, be performed during
            hours other than Tenant's regular business hours so as to minimize
            any disruption of Tenant's normal business activities, and except
            for reasonable downtime during such location, such relocation shall
            not prevent Tenant from using its Rooftop Equipment for its original
            intended purpose. Tenant shall reasonably cooperate

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            with Landlord to effectuate the relocation of Tenant's Rooftop
            Equipment and any Wiring, as shall be required by Landlord. Landlord
            acknowledges that Landlord's rights set forth in this Section
            1.07(c)(xiv) are subject to any priority right of Tenant set forth
            in Section 1.07(b)(ii) above with respect to Tenant's Rooftop
            Equipment in relation to the equipment of other tenants.

      SECTION 1.08 RISERS

      During the Term and subject to availability (such availability to be
determined in good faith in Landlord's sole judgment), Tenant is hereby granted
the following licenses (collectively, the "Riser License"):

      (a) a non-exclusive license to use, a portion of the Building's shafts,
risers and conduits available for telecommunications, data, plumbing, electrical
and chilled water purposes between the Leased Premises and other parts of the
Building (including the roof, but subject to Section 1.07) for the installation
and maintenance of conduits, cables, ducts and other similar devices for the
conduct of Tenant's business at the Leased Premises;

      (b) an exclusive license to use the existing riser space connecting the
Leased Premises to the data center currently existing on the 3rd Level of the
Building; provided that Tenant shall not have access to such riser through any
space leased to, or occupied by, any other tenant or third-party (the "Third
Party Riser Space") (Landlord shall, upon reasonable prior notice, grant Tenant
reasonable access to the Building's common areas in connection with Tenant's
installations and maintenance in such riser); provided, however, solely in the
case of an emergency, Tenant may have access to the Third Party Riser Space to
the extent necessary to access any risers under the Riser License so long as
Tenant has no other feasible alternative to access Tenant's risers and Tenant
informs Landlord of its intention to access such Third Party Riser Space and the
reasons therefor prior to any such access and; provided further, that in
connection with any such access Tenant agrees (A) not to unreasonably interfere
with, annoy or disturb any other tenant or third party while accessing the Third
Party Riser Space and (B) to restore the Third Party Riser Space to the original
condition after such access. Tenant shall be liable for any damage to the Third
Party Riser Space in connection with any access thereto and shall indemnify and
hold harmless Landlord and any other tenant or third party in connection
therewith; and

      (c) an exclusive license to use the existing mail risers, which Landlord
agrees that such mail risers shall remain in place during the Term.

Tenant may, at Tenant's sole cost, (i) relocate the motors and other related
equipment currently located at or near the bottom of the mail risers to the 6th
Level of the Building and (ii) cap such mail risers at the top floor of the
Leased Premises. Notwithstanding the foregoing, Tenant shall, at Tenant's sole
cost, promptly cap such mail risers upon notice from Landlord that any Levels of
the Building served by such mail risers have been leased to a third-party.
Tenant shall not be charged an access fee for Tenant's utilization of such space
in the Building risers, shafts and conduits pursuant to the terms of this
Section 1.08. Subject to (i) Landlord's prior approval

                                        9

<PAGE>

(which shall not be unreasonably withheld, delayed or conditioned), Tenant may
assign its interest in the Riser License to a permitted assignee of Tenant's
rights under this Lease in conjunction with Tenant's assignment of all of its
rights under this Lease to such permitted assignee and (ii) Landlord's prior
approval (which may be withheld in Landlord's sole discretion and shall include
approval of the proposed third-party telecommunications provider), Landlord
shall permit Tenant's third-party telecommunication provider to use the Riser
License for the purpose of installing cabling and other equipment necessary to
provide telecommunications services to the Leased Premises. Tenant agrees to
indemnify and hold Landlord harmless from and against any loss, claim, liability
or expense incurred by Landlord in connection with Tenant's use of the Riser
License or the Building's shafts, risers and conduits in connection therewith.

                                    ARTICLE 2
                   TERM; USE; BASE RENTAL; OPERATING EXPENSES

      SECTION 2.01 TERM

      (a) Subject to and upon the terms and conditions set forth in this Lease,
this Lease shall commence on the Commencement Date and shall continue in force
for the Term (unless sooner terminated in accordance with its terms).

      (b) Should the Term commence on a date other than the Commencement Date,
Landlord and Tenant will, at the request of either, execute a declaration
specifying the beginning date of the Term. In such event, Rent under this Lease
shall not commence until said revised commencement date, and the Term shall
thereupon commence and the expiration date shall be extended so as to give
effect to the full stated term.

      SECTION 2.02 USE

      (a) The Leased Premises shall be used and occupied by Tenant solely as
general, administrative and executive offices (including such ancillary uses in
connection therewith as shall be reasonably required by Tenant in the operation
of its business); except, that in no event may any of the following be permitted
in the Leased Premises:

                  (i) offices or agencies of a foreign government or political
            subdivisions thereof;

                  (ii) offices of any governmental bureau or agency of the
            United States or any state or political subdivision thereof;

                  (iii) personnel agencies; or

                  (iv) customer service offices of any public utility company.

      (b) The Leased Premises may not be used for any of the following uses
(except to the extent such use is ancillary to any other use expressly permitted
under this Lease):

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<PAGE>

                  (i)   health care activities;

                  (ii)  schools or other training or educational uses;

                  (iii) clerical support services;

                  (iv)  reservation centers for airlines or travel agencies;

                  (v)   retail or restaurant use;

                  (vi)  studios for radio, television or other media; or

                  (vii) storage (except as expressly provided otherwise in
            Section 2.02(d)).

      (c) The Leased Premises shall not be used for any purpose which would, in
Landlord's reasonable opinion, diminish the first-class character of the Project
or any part thereof, create unreasonable or excessive elevator or floor loads,
interfere with any of the operations of the Project or any part thereof or the
proper and economic heating, air-conditioning, cleaning or other servicing of
the Project or any part thereof or unreasonably interfere with the use of the
other areas of the Project by any other tenants.

      (d) Notwithstanding anything to the contrary set forth in Section 2.02(a),
(i) use of the Roof Space and the Rooftop Equipment Closet shall be governed by
Section 1.07 and (ii) that portion of the Leased Premises located on Levels B-l
and B-2 may be used for storage and general, administrative office use.
Notwithstanding anything to the contrary in Article 3, with respect to that
portion of the Leased Premises located on Levels B-l and B-2 that is designed
for storage use, Landlord shall only provide services of the nature, and to the
extent, appropriate and customary for space used primarily for storage.

      SECTION 2.03 BASE RENTAL

      (a) Tenant hereby agrees to pay the Base Annual Rental (hereinafter
sometimes called "Base Rental") per year. Tenant shall also pay, as part of
Additional Rent, all such other sums of money as shall become due from and
payable by Tenant to Landlord under this Lease. Landlord shall have the same
remedies for default in the payment of Additional Rent as are available to
Landlord in the case of a default in the payment of Base Rental. Such Base
Rental, together with Tenant's Share of Forecast Operating Expenses (hereinafter
defined), shall be due and payable in 12 equal installments on or before the
first day of each calendar month during the Terra, and Tenant hereby agrees to
so pay such Rent to Landlord at Landlord's address as provided herein (or such
other address in the continental United States as may be designated by Landlord
from time to time) monthly in advance without demand. If the Term commences on a
date other than the first day of a month or terminates on a date other than the
last day of a month, then the installments of Base Rental and Additional Rent
for such month or months shall be prorated. All past due installments of Rent
shall bear interest, so long as the tenant hereunder is Transcontinental Gas
Pipe Line Corporation, from the 5th day after such due date, and otherwise

                                       11

<PAGE>

from the due date until the date such amount is paid (both dates inclusive), at
an annual interest rate equal to the lesser of (i) 8% and (ii) the maximum
non-usurious rate of interest permitted by the applicable laws of the State of
Texas, as determined by reference to the indicated (weekly) rate ceiling (as
defined and described in Texas Revised Civil Statutes, Article 5069-1.04 (or any
successor statute), as amended) at the applicable time in question. Tenant shall
pay to Landlord all items of Rent required to be paid by Tenant under this
Lease, without notice or demand, and without any set-off, counterclaim,
abatement or deduction whatsoever, except as may be otherwise expressly set
forth in this Lease.

      (b) Tenant shall receive a credit (the "Base Rental Credit") to be applied
against Base Rental in accordance with the terms of Schedule 3, provided that,
as of the date such credit is to be applied an Event of Default under Section
5.10(a)(i), (iii), (iv), (v), (vi) or (vii) (each a "Material Event of
Default") shall not exist.

      The Base Rental Credit shall be applied against monthly Base Rental
amounts due under this Lease. In the event the terms of this Lease provide for
the abatement of Base Rental during any period, the Base Rental Credit
applicable during such period shall be adjusted to apply only to that portion of
the Leased Premises for which Base Rental is not abated.

      SECTION 2.04 NET LEASE

      This Lease is a net lease and Base Rental shall be paid to Landlord
absolutely net of all costs and expenses. The provisions for payment of Actual
Operating Expenses by means of periodic payment of Tenant's Share of Forecast
Operating Expenses and the Operating Expense Adjustment are intended to pass
through to Tenant, and reimburse Landlord for, all costs and expenses of the
nature described in Section 2.05 incurred in connection with ownership,
management and operation of the Project and such additional facilities now and
in subsequent years as may be determined by Landlord to be included within the
Project, subject to the exclusions and limitations set forth herein.

      SECTION 2.05 OPERATING EXPENSES

      (a) "Actual Operating Expenses" means all Operating Expenses of the
Project. All Operating Expenses shall be computed on an accrual basis and
determined in accordance with generally accepted accounting principles which
shall be consistently applied. The term "Operating Expenses" as used herein
shall mean all expenses, costs and disbursements (except as specifically
excluded in this Section 2.05) of every kind and nature which Landlord shall pay
or become obligated to pay because of or in connection with the ownership,
management and operation of the Project including but not limited to the
following:

            (1)   Wages and salaries and related expenses and benefits of all
                  on-site and off-site employees engaged in the supervision,
                  operation and maintenance, or access control of the Project
                  and personnel who may provide traffic control relating to
                  ingress and egress to and from the Project to the

                                       12

<PAGE>

                  adjacent public streets and the costs (based upon fair market
                  rental rates) of a management office in the Project.

            (2)   All supplies, tools, equipment and materials used in the
                  operation and maintenance of the Project and any lease
                  payments made by Landlord for any equipment leased in the
                  operation and maintenance of the Project.

            (3)   Cost of all utilities for the Project including the cost of
                  water and power, heating, lighting, air conditioning and
                  ventilating for the Project (excluding those costs separately
                  payable by specific tenants).

            (4)   Cost of all maintenance and service agreements for the Project
                  and the equipment therein, including access control service,
                  window cleaning, elevator maintenance, landscaping and
                  janitorial services.

            (5)   Cost of all insurance relating to the Project including the
                  cost of casualty and liability insurance and rental abatement
                  insurance applicable to the Project and Landlord's personal
                  property used in connection therewith.

            (6)   All taxes and assessments and governmental charges with
                  respect to the Project whether federal, state, county or
                  municipal, and whether they be by taxing districts or
                  Governmental Authorities presently taxing the Leased Premises
                  or by others, subsequently created or otherwise, and any other
                  taxes and assessments attributable to the Project or its
                  operation. It is agreed that Tenant shall be responsible for
                  ad valorem taxes on its personal property and on the value of
                  leasehold improvements to the extent that same exceed building
                  standard improvements as defined on Exhibit C.

            (7)   Cost of repairs and general maintenance of the Project
                  (excluding repairs and general maintenance paid by proceeds of
                  insurance or by Tenant or other third parties, and alterations
                  attributable solely to preparation of space for occupancy by
                  tenants of the Building other than Tenant).

            (8)   Amortization (together with reasonable financing charges) of
                  the cost of supplying and installing capital investment items
                  which are intended for the purpose of reducing operating costs
                  or which may be required by any Governmental Authority. All
                  such costs shall be amortized over the reasonable life Of the
                  particular capital investment items with the reasonable life
                  and amortization schedule being determined in accordance with
                  generally accepted accounting principles but in no event to
                  extend beyond the reasonable life of the Building.

                                       13

<PAGE>

            (9)   Landlord's central accounting costs and audit fees
                  attributable to the Project.

            (10)  The cost of payment and performance of Landlord's obligations
                  with respect to all of the above expenses in connection with
                  the park (but excluding the water wall) adjacent to or located
                  at the Project, the skybridges which connect the Building to
                  the Garage and other structures and the driveways serving the
                  Project.

            (11)  All costs and expenses of any management administrative office
                  of the Project.

            (12)  Any lease payments made by Landlord for equipment used in the
                  operation and maintenance of the Project.

            (13)  A management cost recovery equal to 2% of Tenant's Base Rental
                  plus 2% of Tenant's Share of Actual Operating Expenses (net of
                  the management cost recovery).

            (14)  All costs incurred by Landlord in order to ensure the
                  Project's compliance with any Legal Requirement, or any other
                  requirement, imposed by any insurer but only with, respect to
                  Legal Requirements or other requirements that may come into
                  effect after the Commencement Date, unless such costs are due
                  to on-going compliance by Landlord in accordance with any
                  Legal Requirement or other requirement in which case such
                  costs shall be included in Operating Expenses even if such
                  requirements came into effect prior to the Commencement Date,
                  and excluding any costs incurred by Landlord in connection
                  with making the restrooms on any floor of the Building
                  occupied exclusively by one tenant (other than Tenant)
                  compliant with the requirements of the Americans with
                  Disabilities Act.

      (b) Landlord hereby agrees that, in addition to any exclusions expressly
described in Section 2.05(a), Operating Expenses shall not include the
following:

            (1)   Costs of repairs, replacements or other work occasioned by
                  casualties or condemnation, to the extent covered by insurance
                  proceeds, or to the extent Landlord fails to comply with its
                  obligations to insure the Building in accordance with Section
                  5.12, such repairs, replacements or other work occasioned by
                  casualties not covered by insurance proceeds which would have
                  been covered by insurance proceeds had Landlord not failed to
                  insure the Building in accordance with Section 5.12, or to the
                  extent compensated by Governmental Authorities in connection
                  with the exercise of the right of eminent domain.

                                       14

<PAGE>

            (2)   Leasing commissions, attorneys' fees, costs, disbursements and
                  other expenses incurred by Landlord or its agents in
                  connection with the solicitation of, advertising for,
                  negotiating with or entering into leases or other prospective
                  tenancy arrangements for space in the Project (including in
                  connection with any assumption by Landlord of a prospective
                  tenant's existing lease or payments made to satisfy a
                  prospective tenant's lease obligations with respect to any
                  such existing lease), or in connection with negotiations,
                  disputes or enforcement of agreements with such prospective
                  tenants, tenants or other occupants of the Project, marketing
                  or leasing consultants, management agents, purchasers, ground
                  lessors, prior owners or mortgagees of the Building including
                  leasing commissions and fees of attorneys or of marketing or
                  leasing consultants.

            (3)   Tenant allowances, tenant concessions, workletters, and other
                  costs or expenses (including permit, license and inspection
                  fees) incurred in completing, fixturing, furnishing,
                  renovating or otherwise improving, decorating or redecorating
                  space for tenants or other occupants of the Building, or
                  vacant, leaseable space in the Building, including space
                  planning/interior design fees relating thereto.

            (4)   Depreciation or other "non-cash" expense items and
                  amortization, except for amortization charges as provided for
                  in Section 2.05(a)(8).

            (5)   Except as expressly included under Section 2.05(a)(8) and
                  (14), costs of a capital nature, including capital additions,
                  capital improvements, capital alterations, capital
                  replacements, capital equipment, capital tools and capital
                  redesign, all in accordance with generally accepted accounting
                  principles, consistently applied.

            (6)   Any costs of any service or item sold or provided to tenants
                  or other occupants for which Landlord or Landlord's managing
                  agent (i) has been or is entitled to be reimbursed by such
                  tenants or other occupants for such service or item, other
                  than under provisions similar to this Section 2.05 or (ii) has
                  been or is reimbursed by insurance or otherwise compensated by
                  parties other than tenants of the Project to include
                  replacement of any item covered by a warranty.

            (7)   Costs or expenses (including fines, penalties and legal fees)
                  incurred due to the violation by any Landlord Party, any
                  tenant or other occupant of the Building, of any terms and
                  conditions of the leases in the Building, or any applicable
                  Legal Requirements that would not have been incurred but for
                  such violation by any Landlord Party, tenants or other
                  occupants of the Building, it being intended that each party
                  shall be responsible for the

                                       15
<PAGE>

                  costs resulting from its own violation of such leases and
                  Legal Requirements as same shall pertain to the Building.

            (8)   Penalties for late or non-payment, including penalties for
                  late or non-payment of taxes, equipment lease payments or
                  other expenses, except to the extent attributable to any late
                  or non-payment of Tenant's Share of Forecast Operating
                  Expenses.

            (9)   Payments to any Affiliate of Landlord for services on or to
                  the Project (or any portion thereof), or for goods, supplies
                  or other materials, in each case, only to the extent that the
                  costs of such services, goods, supplies or materials exceed
                  the costs that would have been paid had the services, goods,
                  supplies or materials been provided by reputable Persons
                  unaffiliated with Landlord.

            (10)  Payments of principal, finance charges or interest on debt or
                  amortization on any mortgage, deed of trust or other debt, and
                  rental payments (or increases in same) under any ground or
                  underlying lease or leases (except to the extent (i) otherwise
                  expressly included in Operating Expenses under Section 2.05(a)
                  or (ii) such payments may be made to pay or reimburse, or may
                  be measured by, real estate taxes or insurance otherwise
                  included in Operating Expenses).

            (11)  Costs of (including compensation paid to clerks, attendants or
                  other persons) operating any commercial concessions (such as a
                  snack bar, restaurant or newsstand) operated by Landlord or
                  any Affiliate of Landlord to the extent such costs are offset
                  by income received therefrom by Landlord.

            (12)  Costs of correcting defects, including latent defects, in the
                  construction of the Project.

            (13)  Contributions to operating expense reserves, tenant
                  improvements reserves, leasing commissions reserves or capital
                  improvements reserves.

            (14)  Contributions to political or charitable organizations.

            (15)  Costs incurred in removing the property of former tenants or
                  other occupants of the Building.

            (16)  Costs or fees relating to the defense of Landlord's title to
                  or interest in the Project, or any part thereof.

            (17)  Costs associated with the operations of the business of the
                  entity which constitutes "Landlord" or "Landlord's managing
                  agent" that are unrelated to the costs of operating the
                  Project, including, without limitation,

                                       16
<PAGE>

                  Landlord or Landlord's managing agent's general corporate
                  overhead and general administrative expenses, legal, risk
                  management and corporate and/or partnership accounting and
                  legal costs, mortgages, debt costs and other financing
                  charges, asset management fees, administrative fees, any costs
                  that would normally be considered included in a management fee
                  (e.g., property accounting charges, local area network and
                  wide area network charges, travel expenses for company
                  meetings or training), placement/recruiting fees/costs for
                  employees to the extent such employees are not assigned to the
                  Project, real estate licenses and other industry
                  certifications, employee parking and transportation charges,
                  tickets to special events, costs of defending any lawsuits,
                  costs of syndicating, financing, mortgaging or hypothecating
                  any of Landlord's interests in the Project, bad debt loss,
                  rent loss or any reserves thereof, and costs incurred in
                  connection with any disputes between Landlord and/or
                  Landlord's management agent and their employees, tenants or
                  occupants and providers of goods and services to the Project.

            (18)  Wages, salaries, fringe benefits and any other form of
                  compensation paid to any executive employee of Landlord and/or
                  Landlord's managing agent above the level of "senior property
                  manager" and wages, salaries, fringe benefits and other forms
                  of compensation of any other employee of Landlord and/or
                  Landlord's managing agent to the extent unrelated to the
                  maintenance and operation of the Project.

            (19)  Any rental payments and related costs paid under any ground
                  lease of land underlying all or any portion of the Project.

            (20)  Construction costs for the construction of (i) any additional
                  floors to the Building and (ii) any additional buildings on
                  the Land.

            (21)  Landlord's gross receipts taxes for the Project, personal and
                  corporate income taxes, inheritance and estate taxes,
                  franchise, gift and transfer taxes.

            (22)  Any fines, costs, late charges, liquidated damages, penalties,
                  tax penalties or related interest charges, imposed on Landlord
                  or Landlord's managing agent, except, in each case, to the
                  extent attributable to any late or non-payment of Tenant's
                  Share of Forecast Operating Expenses.

            (23)  Any above Building-standard services provided to any other
                  tenant or occupant of the Building, including, above
                  Building-standard cleaning services, but only to the extent
                  such services exceed Building-standard services.

                                       17
<PAGE>

            (24)  Other than with respect to the Project, any office rental and
                  any parking charges for the Landlord's and/or Landlord's
                  managing agent's management, engineering, maintenance,
                  security, parking or other vendor personnel, in each case
                  other than reasonable costs and expenses connected therewith.

            (25)  All advertising and promotional costs intended to attract new
                  tenants to the Building.

            (26)  Any increase in the cost of Landlord's insurance caused by a
                  specific use of a tenant (other than Transcontinental Gas Pipe
                  Line Corporation) or by Landlord.

            (27)  Any cost or expense related to removal, cleaning, abatement or
                  remediation of any Hazardous Substance (hereinafter defined),
                  including toxic mold, in or about the Project, and including
                  Hazardous Substances in the ground water or soil, but only to
                  the extent any of the same arose prior to the Commencement
                  Date.

            (28)  Rentals and other related expenses incurred in leasing air
                  conditioning systems, elevators or other equipment, in each
                  case other than for temporary use due to repairs, replacements
                  or other work, the cost of which if purchased would be
                  excluded from Operating Expenses as a capital cost, to the
                  extent such expenses exceed the sum that would have been
                  allocated to the relevant year had such equipment been
                  purchased and the cost thereof amortized as provided for in
                  Section 2.05(a)(8).

            (29)  Costs, other than those incurred in connection with ordinary
                  maintenance or repair, for sculptures, paintings, fountains or
                  other objects of art or the display of such items.

      (c) "Tenant's Share of Forecast Operating Expenses" means Tenant's Share
of Actual Operating Expenses as reasonably projected by Landlord for the subject
calendar year. 'Tenant's Share" means a fraction, the numerator of which is the
Net Rentable Area of the Leased Premises and the denominator of which is the
greater of (1) 95% of the Net Rentable Area of the Building and (2) the total
Net Rentable Area leased to and occupied by tenants of the Building. For each
calendar year, a statement of the projected amount of Tenant's Share of Forecast
Operating Expenses shall be furnished by Landlord to Tenant not later than 30
days prior to the beginning of the applicable calendar year. Concurrently with
each installment payment of Base Rental, Tenant shall pay to Landlord
one-twelfth (1/12th) of Tenant's Share of Forecast Operating Expenses for the
applicable calendar year.

            (d) (i) If Tenant's Share of Actual Operating Expenses for any
            calendar year is greater than payments previously made by Tenant on
            account of Tenant's

                                       18

<PAGE>

            Share of Forecast Operating Expenses, then Tenant shall pay to
            Landlord, within 30 days after Tenant's receipt of the annual
            statements referred to below, the amount of such excess. However, if
            Tenant's Share of Actual Operating Expenses for such calendar year
            is less than payments previously made by Tenant on account of
            Tenant's Share of Forecast Operating Expenses, then Landlord shall
            pay to Tenant within 30 days after Tenant's receipt of such
            statements the amount of such difference.

                  (ii) Within 150 days (or as soon thereafter as reasonably
            practicable but in no event later than 180 days after conclusion of
            the calendar year) after the conclusion of a calendar year all or
            any portion of which is within the Term (including the last calendar
            year of the Term, Landlord and Tenant agreeing that the provisions
            of this Section 2.05(d) shall survive the expiration or sooner
            termination of this Lease), Landlord shall deliver to Tenant a
            written statement ("Landlord's Operating Expense Statement")
            itemized in reasonable detail and certified by Landlord to Tenant,
            setting forth Actual Operating Expenses for the subject calendar
            year and comparing Tenant's Share of Forecast Operating Expenses to
            Tenant's Share of Actual Operating Expenses for the subject calendar
            year.

                  (iii) Tenant, upon written, notice to Landlord delivered no
            later than 90 days after Tenant's receipt of Landlord's Operating
            Expense Statement, shall have the right, at Tenant's expense, to
            audit ("Tenant's Audit") the Operating Expenses for such calendar
            year (but only to the extent such expenses are included in the
            relevant Landlord's Operating Expense Statement). If Tenant fails to
            deliver such notice within such 90-day period, such statement shall
            be deemed conclusively binding upon Tenant. Tenant's Audit shall be
            conducted only on Business Days during business hours at Landlord's
            offices. In connection with any such audit, Tenant shall not employ
            any Person who is to be compensated, in whole or in part, on a
            contingency fee basis.

                  Tenant shall promptly deliver, or shall cause to be promptly
            delivered, to Landlord a written report ("Tenant's Audit Report")
            setting forth the findings of Tenant's Audit. Within 20 days after
            Landlord's receipt of Tenant's Audit Report, Landlord shall notify
            Tenant whether (1) Landlord agrees with the findings of Tenant's
            Audit Report or (2) Landlord in good faith disputes the findings of
            Tenant's Audit Report. In the event Landlord fails to deliver the
            foregoing notice within such 20-day period, the findings set forth
            in Tenant's Audit Report shall be deemed conclusively binding upon
            Landlord. In the event Landlord timely notifies Tenant of its good
            faith dispute of the findings of Tenant's Audit Report (such notice
            being the "Dispute Notice"), the parties shall negotiate in good
            faith to resolve such dispute. In the event the parties are unable
            to resolve such dispute within 30 days after Tenant's receipt of the
            Dispute Notice, either party may elect, by written notice (the
            "Audit Arbitration Election

                                       19

<PAGE>

            Notice") to the other party, to have the dispute resolved by
            arbitration before a single arbitrator in accordance with the
            following arbitration procedure:

                  (1)   For the 20-day period immediately after delivery of the
                        Audit Arbitration Election Notice, Landlord and Tenant
                        shall negotiate, in good faith, to select a mutually
                        agreeable arbitrator. If Landlord and Tenant fail to
                        agree on an arbitrator within such 20-day period,
                        Landlord shall, on behalf of the parties, promptly
                        request the American Arbitration Association (the "AAA")
                        to appoint an arbitrator for the purposes set forth
                        herein. The AAA shall be instructed to appoint, as
                        arbitrator, an individual with the following
                        qualifications: ten (10) years' current and active
                        experience in the business of the management of
                        commercial rental properties in Houston, Texas, and such
                        individual has never been a direct or indirect employee,
                        Affiliate or agent of either Landlord or Tenant. The AAA
                        shall be instructed to appoint such arbitrator (i) in
                        accordance with the AAA's standard procedures governing
                        the selection of an arbitrator on behalf of arbitrating
                        parties and (ii) within 20 days after Landlord's request
                        therefor. The AAA's selection of arbitrator shall be
                        binding upon Landlord and Tenant.

                  (2)   The arbitrator shall render its decision within 30 days
                        after the date of appointment.

                  (3)   With respect to the disputed item of Operating Expense
                        only, the arbitrator shall select either Landlord's
                        Operating Expense Statement or Tenant's Audit Report as
                        the one that, in the arbitrator's reasonable and
                        professional judgment, most accurately reflects the
                        terms of this Lease.

                  (4)   The arbitrator's decision shall be final and binding
                        upon the parties. Landlord shall pay the fees of the
                        arbitrator in the event the arbitrator's decision
                        selects Tenant's Audit Report. Tenant shall pay the fees
                        of the arbitrator in the event the arbitrator's decision
                        selects Landlord's Operating Expense Statement.

            In the event any final determination of Tenant's Audit (either by
            Landlord's deemed approval of the findings of Tenants' Audit Report
            or by arbitration in accordance with the foregoing (as applicable))
            identifies any overpayment or underpayment in Operating Expenses,
            then, within 30 days after such final determination, Landlord shall
            pay the amount of any such overpayment to Tenant or Tenant shall pay
            the amount of any such underpayment to Landlord (as applicable).

                                       20

<PAGE>

                  (iv) All sums payable by Tenant under this Section 2.05 shall
            be deemed Additional Rent.

      (e) If the Term commences or terminates as to any portion of the Leased
Premises at any time other than the first day of a calendar year, Tenant's Share
of Actual Operating Expenses referred to in this Section 2.05 shall be prorated
accordingly.

      (f) Notwithstanding any other provision herein to the contrary, it is
agreed that in the event the Building is not 95% occupied during any year or in
the event all of the Building is not provided with building standard services
during any year, an adjustment shall be made in computing each component of the
Actual Operating Expenses for such year that varies with occupancy so that the
Actual Operating Expenses shall be computed for such year as though the Building
had been fully occupied during such year.

                                    ARTICLE 3
                                    SERVICES

      SECTION 3.01 SERVICES TO BE FURNISHED BY LANDLORD

      During the Term, Landlord shall furnish (as part of Operating Expenses of
the Project) to Tenant the following services for so long as Tenant is occupying
the Leased Premises:

      (a) Regardless of season or climate, Landlord shall provide hot and cold
water to base building HVAC equipment as necessary to satisfy demand of comfort
related equipment within the Leased Premises on the Building Standard Days
during the Building Standard Hours. Landlord shall provide the same at cost on
days other than Building Standard Days and at times other than Building Standard
Hours upon request of Tenant, who shall bear the entire cost thereof. Routine
maintenance and electric lighting service for all public areas, service areas,
and common areas of the Building in the manner and to the extent deemed
appropriate by Landlord.

      (b) Janitorial services on all Business Days as set forth on Schedule 9
hereto; provided, however, if any of Tenant's floor coverings or other
improvements are other than building standard, Tenant shall pay the additional
cleaning cost attributable thereto..

      (c) Sufficient electrical capacity will be distributed to the panel boxes
located at the core of each floor of the Leased Premises to operate (i)
equipment of a low voltage electrical rating (120/208 volts) and (ii) equipment
of a high voltage electrical rating (277/480 volts) to the extent that the total
design load within the Leased Premises does not exceed six (6) watts per square
foot of net rentable area, such related electrical design load to be hereinafter
referred to as the ("Building Standard Rated Electrical Design Load"). In
addition to the foregoing, Tenant acknowledges that the power available in the
Building standard bus duct at each floor on which the Leased Premises are
located will have a total (i.e., inclusive of the above-described Building
Standard Rated Electrical Design Load) capacity available to Tenant of at least
six (6) watts per

                                       21

<PAGE>

square foot of net rentable area contained on such floor. Tenant shall pay to
Landlord the cost of electricity consumed in excess of the Building Standard
Rated Electrical Design Load as determined by meter, or if not metered, as
otherwise reasonably estimated by Landlord (provided that if the Leased Premises
is not separately metered, Landlord shall provide Tenant with reasonable
supporting documentation for Landlord's calculation of such costs, sufficient to
reasonably enable Tenant to confirm the basis of Landlord's calculations). Such
cost of electricity shall include (1) any actual accounting expenses incurred by
Landlord in connection with the metering thereof, (2) any taxes or other charges
related to such electricity or the supply thereof and (3) if any tax is imposed
upon Landlord's receipts from the sale or resale of electricity to Tenant,
Tenant shall reimburse Landlord for such tax, if and to the extent permitted by
applicable Legal Requirements.

            If Tenant's electrical equipment and lighting require electrical
      circuits, transformers or other additional equipment in excess of Tenant's
      pro rata share (based on the Net Rentable Area of the Leased Premises
      relative to the Net Rentable Area of the Building) of the Building's
      electrical or heating, ventilation and air conditioning systems, Tenant
      may (at Tenant's cost, including the cost to design, install, maintain and
      replace the additional electrical equipment (including the meters))
      install the same, provided such installation is compatible with existing
      Building systems, will not compromise Landlord's ability to provide
      services to Tenant or other tenants of the Building and will not be
      burdensome to the Building or to Landlord, in Landlord's sole opinion, and
      Tenant shall pay all operating costs related to that requirement
      (including the cost of electricity, water or other services consumed
      through, or in connection with, the additional electrical equipment). The
      method of design and installation of any additional electrical equipment
      (including any related meter) required by Tenant shall be subject to the
      prior written approval of Landlord and Tenant (such approval by Tenant not
      to be unreasonably withheld) and shall be performed by Landlord at
      Tenant's sole cost (including a charge equal to 8% of such cost for the
      review and installation of such additional electrical equipment for
      administrative cost recovery).

      (d) All building standard fluorescent bulb replacement in all areas and
all incandescent bulb replacement in public areas, toilet and rest room areas
and stairwells.

      (e) Access control to the Building (the cost of which is part of Operating
Expenses of the Project) during weekends and after normal working hours during
the week consistent with that provided at Comparable Buildings. Landlord shall
not be liable to Tenant for losses due to theft or burglary (except to the
extent caused by the gross negligence or willful conduct of Landlord, its agents
and employees), or for damages done by unauthorized Persons on the Project or
within the Leased Premises.

      (f) Window cleaning to the extent consistent with Comparable Buildings to
be performed at least once every six (6) months during the Term.

                                       22

<PAGE>

      (g) Non-exclusive passenger elevator service to the Leased Premises and
non-exclusive freight elevator service, in each case, at all times.

      (h) Maintenance of the roof, exterior walls, load-bearing components,
foundation, floor slabs and other structural components, the mechanical,
electrical and plumbing systems, fire control systems, security and access
control systems, the Building common areas, service areas, elevators, exterior
lighting, sidewalks and landscaping of the Project all in a manner consistent
with that provided at Comparable Buildings.

To the extent that the services described above require electricity, gas or
water supplied by public utilities, Landlord's obligations shall require only
that Landlord use commercially reasonable efforts to cause the utilities to
furnish the same and shall be subject to any curtailment of utilities supplied.
Failure by Landlord to any extent to furnish any of the services set forth in
this Section 3.01, or any cessation thereof, shall not render Landlord liable in
any respect for damages to either Person or property, nor be construed as an
eviction of Tenant, nor entitle Tenant to any abatement or setoff of rent, nor
relieve Tenant from fulfillment of any covenant or agreement hereof, except to
the extent expressly provided in Section 3.02. Additionally, if any of the
equipment or machinery used in connection with the Project breaks down, or for
any cause ceases to function properly, Tenant shall have no claim for
constructive eviction, setoff, rebate or abatement of rent or damages on account
of any interruption in service occasioned thereby or resulting therefrom, except
to the extent expressly provided in Section 3.02. Notwithstanding anything to
the contrary in this Article 3, no services other than electrical service and
heating, ventilation, water and air conditioning services shall be provided to
the Rooftop Equipment Closet.

      SECTION 3.02 INTERRUPTION IN ESSENTIAL SERVICES

      (a) The parties agree that there are certain services without which Tenant
cannot occupy the Leased Premises for the purposes for which the Leased Premises
were leased. Such services are adequate heating, ventilation, air conditioning,
electrical service, elevator service, water and plumbing services and janitorial
services (the "Essential Services"). In the event any one or more of the
Essential Services is not provided and the failure to provide such Essential
Service(s) renders all or a portion of the Leased Premises Untenantable for a
continuous period of 3 consecutive Business Days, then the Rent with respect to
that portion of the Leased Premises rendered Untenantable shall abate for the
period commencing on the day immediately after such 3rd consecutive Business Day
until the date upon which such Essential Service is restored.

      (b) After a continuous period of either (i) 45 days during which one or
more of the Essential Services is not provided to 50% or more of the Leased
Premises or (ii) 120 days of interruption in any Essential Service during any
calendar year and, in either case, the failure to provide such Essential Service
renders such portion of the Leased Premises Untenantable for such period, then
Tenant may either terminate this Lease as to the specific portion of the Leased
Premises so affected (provided such portion is, in Landlord's reasonable
opinion, of commercially reasonable configuration and reasonably lettable to
unrelated third-parties), upon giving written notice ("Tenant's Service
Interruption Termination Notice") thereof to Landlord.

                                       23

<PAGE>

Landlord shall be afforded 20 Business Days after receipt of Tenant's Service
Interruption Termination Notice to restore the affected Essential Service, which
restoration within such period shall nullify Tenant's Service Interruption
Termination Notice and this Lease shall continue in full force and effect.
However, in the event Landlord fails to restore the affected Essential Service
within 20 Business Days after Landlord's receipt of Tenant's Service
Interruption Termination Notice, then this Lease shall terminate, to the extent
elected in Tenant's Service Interruption Termination Notice on the 20th day
after expiration of such 20-Business Day period; and neither party shall have
any further obligation or liability hereunder accruing after such date (except
to the extent of any obligation or liability that expressly survives termination
in accordance with the terms hereof).

      SECTION 3.03 KEYS AND LOCKS

      (a) Landlord shall furnish, at Tenant's cost, two (2) keys for each
corridor door entering the Leased Premises. Additional keys will be furnished by
Landlord for an additional charge to Tenant, which shall not exceed Landlord's
Actual Cost, on an order signed by Tenant or Tenant's authorized representative.
All such keys shall remain the property of Landlord. No additional locks shall
be allowed on any door of the Leased Premises without Landlord's permission, and
Tenant shall not make, or permit to be made any duplicate keys, except those
furnished by Landlord. Upon termination of this Lease, Tenant shall surrender to
Landlord all keys of the Leased Premises, and provide Landlord with the
combination and access codes of all locks for safes, safe cabinets and vault
doors, if any, in the Leased Premises.

      (b) Tenant shall have the right, at Tenant's sole cost, to continue to
operate, maintain, repair and, at Tenant's election, replace the existing card
key access system serving the Leased Premises (such existing system together
with any replacements thereof being "Tenant's Access Equipment"), provided (i)
at all times, there shall be reasonable controlled access to the Leased
Premises, either by mechanical lock, card key access system or other similar
system, (ii) at all times, Landlord shall be provided copies of all keys, access
card keys, passwords and codes in order to provide Landlord with access and
(iii) Tenant's Access Equipment shall be integrated and tied-in to the
Building's management system and life safety systems (any modifications, access
or tie-in to such Building systems shall be performed by Landlord's designated
contractor). Upon the expiration or sooner termination of the Term, Tenant
shall, at Tenant's election, either (1) surrender to Landlord Tenant's Access
Equipment (together with all keys, access codes and card keys), at which time,
such equipment shall become the sole property of Landlord or (2) remove Tenant's
Access Equipment from the Leased Premises and repair any damage to the Building
resulting from such removal).

      SECTION 3.04 GRAPHICS

      (a) Subject to the last sentence of this Section 3.04(a), Landlord shall
install, at Tenant's election and at Tenant's expense, at the entrance to
Tenant's suite on each level where Tenant occupies the entire floor either (i)
signage using building standard graphics and materials or (ii) signage using
non-building standard graphics selected by Tenant. Landlord also agrees to
provide and install, at Tenant's expense, a listing of Tenant's name and office
number on the

                                       24

<PAGE>

Building Directory Board except that, notwithstanding the foregoing, no charge
shall be imposed for initial listings delivered to Landlord on or before April
30, 2004. No signs, numerals, letters or other graphics shall be used or
permitted on the exterior of, or which may be visible from outside the Leased
Premises unless approved in writing by Landlord (in its sole discretion).

      (b) Landlord agrees to install, at Tenant's expense and in Landlord's sole
discretion, signage in the Level 2 lobby indicating Tenant's occupancy of the
Leased Premises (i) of a size and scale commensurate with the signage of tenants
leasing or occupying space of comparable square footage in the Building to that
of Tenant and (ii) designed and constructed of materials and in a manner in
keeping with the Building's architectural style and finishes. Tenant shall be
permitted to retain its current company logo in the Level 2 lobby until such
time as Landlord has designed the new signage described in this paragraph.

      (c) Prior to the Commencement Date, Tenant shall remove, at Tenant's
expense, (i) the black, plastic letter graphics mounted on the granite wall of
the Level 2 lobby and (ii) the metal plaques located at various points in the
Level 2 lobby stating the "Williams Company Core Values and Beliefs" previously
installed by Tenant. Tenant, at Tenant's expense, shall be responsible for
restoring the granite surfaces beneath the graphics and plaques to their prior
condition.

      SECTION 3.05 PEACEFUL ENJOYMENT

      Provided this Lease is in full force and effect and subject to Landlord's
rights and remedies upon the occurrence of an Event of Default, Tenant may
peaceably and quietly enjoy the Leased Premises without hindrance by Landlord or
any Person lawfully claiming through or under Landlord subject to the terms of
this Lease and to all Underlying Leases and Underlying Mortgages. It is
understood and agreed that this covenant and any and all other covenants of
Landlord contained in this Lease shall be binding upon Landlord and its
successor only with respect to breaches occurring during its and their
respective ownership of the Landlord's interest in this Lease.

      SECTION 3.06 REPAIRS BY LANDLORD

      Unless otherwise expressly provided herein, Landlord shall not be required
to make any improvements to or repairs of any kind or character to the Leased
Premises during the Term, except such repairs as may be deemed necessary by
Landlord for normal maintenance operations or such repairs that are necessitated
as a result of the gross negligence or willful misconduct of any Landlord Party.
The obligation of Landlord to maintain and repair the Leased Premises shall be
limited to building standard items. Special leasehold improvements shall, at
Tenant's written request, be maintained by Landlord, at Tenant's expense, at a
cost or charge equal to the costs incurred in such maintenance plus a 5%
additional charge to cover overhead.

                                       25

<PAGE>

                                    ARTICLE 4
                SERVICES; ASSIGNMENT AND SUBLETTING; ALTERATIONS;
                       SUBORDINATION; INITIAL IMPROVEMENTS

      SECTION 4.01 PAYMENTS BY TENANT

      Tenant covenants and agrees with Landlord to pay all Rent to Landlord at
the times and in the manner required under this Lease.

      SECTION 4.02 REPAIRS BY TENANT

      Tenant covenants and agrees with Landlord subject to Section 5.15, at its
own cost and expense, to repair or replace any damage or injury done to the
Building, or any part thereof, caused by any Tenant Party, provided, however, if
Tenant fails to make such repairs or replacement promptly and such failure
continues for at least thirty (30) days after delivery of notice by Landlord to
Tenant specifying such failure in reasonable detail, Landlord may, at its
option, make repairs or replacements, and Tenant shall reimburse the reasonable
cost thereof to the Landlord on demand, subject to Section 5.15 and subject to
the provisions of Section 5.06 (which shall exclusively govern the obligations
of the parties with respect to any Casualty Condition). Notwithstanding the
foregoing, except in the case of emergency, if Tenant commences such repairs
within thirty (30) days after delivery of written notice from Landlord to Tenant
specifying such failure in detail and thereafter diligently and continuously
uses reasonable efforts to complete such repairs, the thirty (30) day period
provided above shall be extended by whatever period of time is reasonably
required to complete such repairs; provided, however, that in no event shall
such period be extended beyond any date on which Tenant's failure to complete
such repairs would cause Landlord to be in default under any lease, mortgage,
deed of trust, security agreement or similar document. Notwithstanding the
foregoing, Landlord shall not be required to provide Tenant with any notice
prior to its performance of any such repair or replacement if an emergency shall
exist. For the purposes of this Section 4.02, an "emergency" shall be deemed to
exist if Landlord in good faith believes that a condition within the Leased
Premises or any other portion of the Project presents a significant possibility
of personal injury or damage to property.

      SECTION 4.03 CARE OF LEASED PREMISES

      Tenant covenants and agrees with Landlord not to commit or allow any waste
or damage to be committed on any portion of the Leased Premises and at the
termination of this Lease, by lapse of time or otherwise, to deliver the Leased
Premises to Landlord in as good condition as existing as of the Commencement
Date, ordinary wear and tear, casualty loss, condemnation and repairs and
maintenance that are Landlord's obligations hereunder excepted, and upon such
termination of this Lease, Landlord shall have the right to re-enter and resume
possession of the Leased Premises.

      SECTION 4.04 ASSIGNMENT OR SUBLEASE

                                       26
<PAGE>

      (a) Except to the extent expressly permitted by Section 4.04(h), Tenant
may not assign or in any manner transfer or encumber this Lease or any interest
herein, or sublet the Leased Premises or any part thereof, or grant any license,
concession, or other right of occupancy to any portion of the Leased Premises,
without the prior written consent of Landlord, which consent may be withheld in
Landlord's sole and absolute discretion, except as expressly provided otherwise
in Section 4.04(b). If granted, Landlord's consent shall be upon such conditions
as Landlord may reasonably impose. Consent by Landlord to any assignment,
subletting, use or occupancy, or transfer shall not operate to relieve Tenant
from any covenant or obligation hereunder except to the extent, if any,
expressly provided for in such consent, nor shall such consent be deemed to
relieve Tenant from obtaining Landlord's consent to any subsequent assignment,
transfer, lien, charge, subletting, use or occupancy.

      (b) In the event Tenant desires to assign this Lease or sublet the Leased
Premises or any part thereof and Landlord's consent is not required under
Section 4.04(h), Tenant shall give Landlord written notice of such desire (and
the proposed effective date thereof) at least 30 days in advance of the date on
which Tenant desires to make such assignment or sublease and such notice shall
include (i) a draft of the proposed assignment or sublease, (ii) the name and
address of the proposed subtenant or assignee, (iii) the financial and other
significant terms of the proposed sublease or assignment (including a
calculation of the Profit (as hereinafter defined), if any, to be realized in
the sublease or assignment), (iv) evidence of the financial strength (including
audited financial statements if available or other financial statements
reasonably satisfactory to Landlord) of the subtenant or assignee and (v) such
other information as Landlord may reasonably require (collectively, the
"Required Information"). Landlord shall, within 20 days after its receipt of
such notice and all the Required Information (such 20-day period shall not
commence until Landlord has received all the Required Information), notify
Tenant that Landlord either (such notification being "Landlord's
Assignment/Subletting Response");

            (1)   elects to terminate this Lease as to the space so affected as
                  of the date so specified by Tenant in which event Tenant shall
                  be relieved of all further obligation hereunder as to such
                  space (except to the extent of all obligations that expressly
                  survive termination in accordance with the terms hereof),
                  unless Tenant delivers notice to Landlord within 10 Business
                  Days after Tenant's receipt of Landlord's
                  Assignment/Subletting Response notifying Landlord that Tenant
                  elects to withdraw its request to sublet or assign, in which
                  case, such termination shall be nullified and this Lease shall
                  remain in effect as if no such consent was requested; or

            (2)   approves Tenant's request to assign this Lease or sublet such
                  space, provided that the following requirements are satisfied:

                  (A)   the use of the Leased Premises or portion to be sublet
                        (as applicable) by such proposed assignee or subtenant
                        is permitted

                                       27

<PAGE>

                        hereunder and does not violate any Underlying Mortgage,
                        Underlying Lease;

                  (B)   in the event of a proposed subletting and after giving
                        effect thereto, there shall not be more than two
                        subtenants and/or licensees (excluding Tenant and any
                        Affiliate of Tenant) on any floor of the Leased
                        Premises; and

                  (C)   all the conditions set forth in Section 4.04(f) are
                        satisfied.

      (c) If Landlord approves Tenant's request to assign this Lease or sublet
any portion of the Leased Premises, 50% of any Profit realized by Tenant as a
result of such assignment or sublease shall, to the extent such Profit is
immediate, be due and payable by Tenant to Landlord upon the execution of an
assignment or sublease, and, to the extent such Profit is deferred, be payable
to Landlord, as it accrues. For the purposes of this Section 4.04, the term
"Profit" means the excess of (i) all sums payable pursuant to any assignment or
sublease or any other instrument executed between Tenant and the sublessee or
assignee as consideration for the use and occupancy of the applicable space
determined on a monthly per square foot basis of Net Rentable Area within the
subleased or assigned premises, over (ii) the sum of (x) all Rent payable by
Tenant pursuant to this Lease determined on a monthly per square foot basis of
Net Rentable Area within the premises covered by the sublease or assignment, and
(y) actual costs paid to independent third-parties unaffiliated with Tenant
incurred in connection with such sublease or assignment spread over the term of
the sublease or assignment and determined on a monthly per square foot basis of
Net Rentable Area in the subleased or assigned space, multiplied by the number
of months of the term of the assignment or sublease (including commercially
reasonable leasing commissions, legal fees, tenant improvements and transfer
taxes).

      (d) In the event Landlord approves Tenant's request to sublet or assign in
accordance with Section 4.04(b)(2) or otherwise, (i) in the case of a
subletting, Tenant agrees to provide at its expense, direct access from such
sublet space to a public corridor of the Building and (ii) Tenant shall have a
period of 90 days after receipt of Landlord's consent in which to complete an
assignment or subletting on the same terms and conditions in all material
respects as Tenant provided in its notice to Landlord. In the event that any
such proposed assignment or subletting is for a greater term or upon different
economic terms (other than to an immaterial extent) or if a proposed assignment
or subletting is not completed within such 90-day period, then such consent to
assignment or subletting shall expire at the end of such 90-day period and if
Tenant desires to assign or sublet thereafter, Tenant shall once again comply
with the terms of this Section 4.04 as if no prior written notice had been
given. No consent by Landlord to any assignment or sublease shall be deemed to
be consent to a use not permitted under this Lease, to any act in violation of
this Lease (including compliance with all applicable Legal Requirements), or to
any other or subsequent assignment or sublease and no assignment or sublease by
Tenant shall relieve Tenant of any obligation under this Lease.

                                       28
<PAGE>

         (e) With respect to each and every subletting and assignment approved
by Landlord under the provisions of this Lease, it is further agreed that:

            (1)   the form of the proposed assignment or sublease and the form
                  of Landlord's consent shall be reasonably satisfactory to
                  Landlord and shall comply with the provisions of this Section;

            (2)   no sublease shall be for a term ending later than one day
                  prior to the expiration of the Term;

            (3)   no sublease shall be delivered to any subtenant, and no
                  subtenant shall take possession of any part of the Leased
                  Premises, until an executed counterpart of such sublease has
                  been delivered to Landlord and approved by Landlord as
                  required in this Section 4.04;

            (4)   each sublease shall be subject and subordinate to this Lease
                  and to the matters to which this Lease is or shall be
                  subordinate, it being the intention of Landlord and Tenant
                  that Tenant shall assume and be liable to Landlord for any and
                  all acts and omissions of all subtenants and anyone claiming
                  under or through any subtenants which, if performed or omitted
                  by Tenant, would be a default under this Lease; and Tenant and
                  each subtenant shall be deemed to have agreed that upon the
                  occurrence and during the continuation of a default hereunder,
                  Tenant has hereby assigned to Landlord, and Landlord may, at
                  its option, accept such assignment of, all right, title and
                  interest of Tenant as sublandlord under such sublease,
                  together with all modifications, extensions and renewals
                  thereof then in effect, and such subtenant shall, at
                  Landlord's option and upon notice from Landlord, attorn to
                  Landlord pursuant to the then executory provisions of this
                  Lease other than the monetary terms of this Lease, which
                  monetary terms shall be governed by the terms of such
                  sublease, except that Landlord shall not be (A) liable for any
                  previous act or omission of Tenant under such sublease, (B)
                  subject to any counterclaim, offset or defense, which
                  theretofore accrued to such subtenant against Tenant, (C)
                  bound by any previous modification of such sublease not
                  consented to by Landlord, or by any prepayment of more than
                  one month's rent and additional rent under such sublease, (D)
                  bound to return such subtenant's security deposit, if any,
                  except to the extent that Landlord shall receive actual
                  possession of such deposit and such subtenant shall be
                  entitled to the return of all or any portion of such security
                  deposit under the terms of its sublease, or (E) obligated to
                  make any payment to or on behalf of such subtenant, or to
                  perform any work in the subleased space or the Building, or in
                  any way to prepare the subleased space for occupancy, beyond
                  Landlord's obligations under this Lease. The provisions of
                  this subsection shall be self-operative, and no further
                  instrument shall be required to give effect to this provision,
                  provided that the subtenant shall execute and deliver to
                  Landlord any

                                       29
<PAGE>

                  instruments Landlord may reasonably request to evidence and
                  confirm such subordination and attornment;

            (5)   notwithstanding any assignment or subletting or any acceptance
                  of Rent by Landlord from any assignee or subtenant, Tenant
                  shall remain fully liable for the payment of all Rent due and
                  for the performance of all other terms, covenants and
                  conditions contained in this Lease on Tenant's part to be
                  observed and performed, and any default under any term,
                  covenant or condition of this Lease by any subtenant or
                  assignee or anyone claiming under or through any subtenant or
                  assignee shall be deemed to be a default under this Lease by
                  Tenant (but shall be subject to any notice and opportunity to
                  cure provisions contained herein). In connection with the
                  foregoing, Tenant waives any defenses that at law or in equity
                  would limit or release its liability under the preceding
                  sentence. Tenant shall indemnify, defend, protect and hold
                  harmless Landlord from and against any and all losses,
                  liabilities, damages, claims, judgments, fines, suits,
                  demands, costs, interest and expenses of any kind or nature
                  (including reasonable attorneys' fees and disbursements)
                  resulting from any claims that may be made against Landlord by
                  the proposed assignee or subtenant or anyone claiming under or
                  through any subtenant or by any brokers or other Persons
                  claiming a commission or similar compensation in connection
                  with the proposed assignment or sublease, irrespective of
                  whether Landlord shall give or decline to give its consent to
                  any proposed assignment or sublease, or if Landlord shall
                  exercise its right to terminate under this Section; and

            (6)   if the proposed subtenant or assignee is an entity organized
                  under the laws of any jurisdiction other than the United
                  States or any state thereof, or is not a United States
                  citizen, if an individual, such subtenant or assignee shall
                  have waived any immunity to which it may be entitled, and
                  shall be subject to the service of process in, and the
                  jurisdiction of the courts of, the City of Houston and State
                  of Texas.

      (f) If Tenant is a corporation or limited liability company, then any
transfer (directly or indirectly) of this Lease from Tenant by merger,
consolidation or dissolution or any change (directly or indirectly) in ownership
or power to vote a majority of the voting stock or interests in Tenant
outstanding at the time of execution of this instrument (or at any future time)
shall constitute an assignment for the purpose of this Lease; provided, however,
that either (i) the acquisition of any or all stock of a corporate tenant, the
stock of which is listed on either the New York or American Stock Exchange,
NASDAQ or another nationally recognized stock exchange or (ii) the sale or
merger of a corporate tenant into such a corporation, the stock of which is so
listed, shall not itself be deemed to be a violation of this Section 4.04. For
purposes of this Section 4.04, the term "voting stock" shall refer to shares of
stock regularly entitled to vote for the election of Directors of the
corporation involved. If Tenant is a general partnership, joint venture, limited
liability partnership or limited liability company having one or more

                                       30

<PAGE>

corporations as partners or as joint venturers or members, or if Tenant is a
limited partnership having one or more corporations as general partners, the
provisions of the preceding paragraph shall apply to each of such corporations
as if such corporation alone had been the Tenant hereunder. If Tenant is a
general partnership, joint venture or limited liability partnership, then the
transfer of a majority of the partnership interest (or joint venture interest)
in Tenant as existing at the time of execution of this instrument (or at any
future time) shall constitute an assignment for the purpose of this Lease. If
Tenant is a limited partnership, then the assignment of all or any portion of
the interest in a general partner of Tenant shall constitute an assignment for
the purpose of this Lease. For purposes of this Section 4.04 only, an Affiliate
of Tenant shall also include any entity that (1) acquires all or substantially
all of Tenant's assets or (2) is the surviving entity in any merger,
consolidation or reorganization involving all or substantially all of Tenant's
assets.

      (g) In the event that Tenant should request an assignment or sublease,
Tenant agrees to reimburse all of Landlord's reasonable legal expenses incurred
as a result of a review of any such requested assignment or sublease and in the
event Landlord consents to any such assignment or sublease Tenant shall
reimburse Landlord for all fees incurred in connection with documentation of the
same, and all non-legal direct and indirect costs Landlord incurs due to such
assignment or subleasing including providing security service, rubbish removal,
freight elevator operation, janitorial service and similar services. Tenant
further agrees that any tenant improvements or all alterations made to the
Leased Premises to make such space ready for any sublease or assignment shall be
performed by contractors reasonably approved by Landlord at Tenant's expense.
Notwithstanding any assignment or subletting permitted hereunder, Landlord shall
have no obligation to approve any Alteration or Tenant improvements other than
as expressly provided for in this Lease.

            (h) (i) Tenant may assign its interest in this Lease to any
            Affiliate of Tenant (provided the requirements set forth in Section
            4.04(b)(2)(A) and (B) and Section 4.04(f) are satisfied), provided
            at least ten (10) days prior to the anticipated effective date of
            such assignment, Tenant delivers to Landlord (1) a notice setting
            forth the fact of Tenant's intended assignment, the effective date
            of such assignment, the identity, address and business of the
            assignee and the intended use of the Leased Premises by such
            assignee, (2) a certificate by an officer of Tenant to Landlord
            certifying that the assignee is an Affiliate of Tenant, (3) a copy
            of the assignment agreement having been executed by all parties
            thereto and (4) any other information Landlord may reasonably
            request. Any such assignment shall not relieve, release, impair,
            modify or discharge any of Tenant's obligations hereunder and Tenant
            and such assignee shall be jointly and severally liable for all
            obligations hereunder.

                (ii) Tenant may permit any then current Affiliate of Tenant to
            sublet all or part of the Leased Premises for any use permitted
            hereby, provided (1) the requirements set forth in Section
            4.04(b)(2)(A) and (B) and Section 4.04(e) are satisfied, (2) at
            least ten (10) days prior to the anticipated effective date of such
            subletting, Tenant delivers to Landlord (A) a notice setting forth
            the fact of

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<PAGE>

            Tenant's intended subletting, the effective date of such subletting,
            the identity, address and business of the subtenant and the intended
            use of the Leased Premises by such subtenant, (B) a certificate by
            an officer of Tenant to Landlord certifying that the assignee is a
            Related Entity, (C) a copy of the sublease agreement having been
            executed by all parties thereto and (D) any other information
            Landlord may reasonably request. Such sublease shall not be deemed
            to vest in any such Related Entity any right or interest in this
            Lease or the Leased Premises nor shall it relieve, release, impair,
            modify or discharge any of Tenant's obligations hereunder, and (3)
            such sublease is not entered into in connection with or in
            contemplation of the sale or other divestiture of such Affiliate.

                  (iii) Tenant may permit any Affiliate of Tenant to occupy the
            Leased Premises (only for so long as such occupant shall be a
            Affiliate) for general and executive office use; provided that (1)
            no compensation other than intra-corporate cost reimbursement is
            paid therefore, (2) such occupancy shall not be deemed a subletting
            or assignment hereunder, (3) such occupancy shall be subject to all
            of the terms and conditions of this Lease, (4) at least ten (10)
            days prior to the anticipated effective date of such occupancy,
            Tenant delivers to Landlord (A) a notice setting forth the fact of
            Tenant's intended license, the effective date of such license, the
            identity, address and business of the licensee and the intended use
            of the Leased Premises by such licensee, (B) a certificate by an
            officer of Tenant to Landlord certifying that the occupant is an
            Affiliate of Tenant, (C) a copy of the license agreement having been
            executed by all parties thereto and (D) any other information
            Landlord may reasonably request.

                  (iv) Tenant may sublet up to 50,000 square feet of the Leased
            Premises without Landlord's prior consent; provided that (1) any
            such subtenant shall be subject to the provisions of this Lease
            including the density limitations set forth herein, (2) the
            subtenant may only use such space for uses permitted under this
            Lease, (3) at least ten (10) days prior to the anticipated effective
            date of such subletting Tenant shall deliver to Landlord a copy of
            the sublease agreement executed by all parties thereto and (4) such
            sublease shall comply with the provisions of Section 4.04(e)(2),
            (4), (5) and (6). Notwithstanding anything contained herein to the
            contrary, any sublease entered into by Tenant pursuant to this
            Section 4.04(h)(iv) shall be subject to the provisions of Section
            4.04(c) hereof.

      (i) Any attempted assignment, sublease or grant of any license,
encumbrance, concession, or other right of occupancy by Tenant in violation of
the terms and covenants of this Section shall be void.

      SECTION 4.05 ALTERATIONS

      (a) Tenant shall not make, or allow to be made, any alterations or
physical additions (including fixtures) to the Leased Premises ("Alterations")
or install signs at the Leased Premises

                                       32
<PAGE>

which are visible from outside the Leased Premises or install safes, vaults,
filing systems, libraries or other heavy furniture or equipment at the Leased
Premises, without first obtaining the consent of Landlord. Notwithstanding the
foregoing, Landlord shall not unreasonably withhold or delay its consent to any
proposed Alteration, provided that the following requirements are each
satisfied:

                  (i) such Alteration is non-structural, does not affect the
            exterior of the Building and is not visible from outside the
            Building or the Leased Premises;

                  (ii) such Alteration, in Landlord's good faith judgment, will
            not impair the structural integrity of the Building;

                  (iii) such Alteration, in Landlord's good faith judgment, will
            not adversely affect the mechanical, electrical, plumbing, heating,
            air-conditioning, or ventilation systems of the Building;

                  (iv) such Alteration will not, in the aggregate, cost more
            than $100,000 (as reasonably estimated by Landlord);

                  (v) such Alteration is accomplished in a good and workmanlike
            manner and in accordance with all applicable Legal Requirements;

                  (vi) such Alteration does not affect the certificate of
            occupancy issued for the Building or the Leased Premises;

                  (vii) such Alteration does not adversely affect or increase
            the cost of any service furnished by Landlord to Tenant or to any
            other tenant of the Building (as reasonably determined by Landlord),
            unless Tenant agrees in writing to pay for such increase;

                  (viii) such Alteration does not violate any Legal Requirement
            or cause the Leased Premises or the Building to be non-compliant
            with any Legal Requirement; and

                  (ix) Tenant obtains all applicable governmental permits,
            licenses and approvals required in connection with such Alteration.

      (b) Upon Landlord's receipt of a request for approval of any Alteration
(together with Landlord's receipt of all items required to be delivered by
Tenant hereunder (including plans and specifications, to the extent required)),
Landlord shall notify Tenant within 10 Business Days of its receipt of such
items whether Landlord approves Tenant's proposed Alteration, or if not
approved, the specific reasons for such disapproval.

      (c) In connection with any proposed Alteration, Landlord shall be entitled
to retain independent consultants to review the plans and specifications and the
progress of construction of such proposed Alteration. Tenant shall reimburse
Landlord, within 30 days after request

                                       33
<PAGE>

therefor, for all fees and expenses of such consultants (including any
construction management fees paid by Landlord to the property manager not to
exceed 7% of the cost of such Alteration). With respect to any Alterations,
Tenant shall not be charged overhead or supervision fees (in connection with
Landlord's review and approval of Tenant's plans and specification therefor) by
Landlord, provided that such Alterations work is undertaken and carried out by
Tenant's contractors with whom Tenant contracts directly for the construction
and installation of such Alterations.

      (d) All contractors retained by Tenant to perform any Alteration shall be
subject to the prior approval of Landlord. Tenant shall not permit the use of
any contractors, labor, material or equipment supplier in the performance of any
work if such use, in Landlord's judgment, would disturb harmony with any trade
engaged in performing any other work in and about the Project or contribute to
any labor dispute.

      (e) Upon completion of each Alteration, Tenant shall promptly deliver to
Landlord a copy of the final "as built" plans and specifications which shall
depict the actual construction for all Alterations existing at the Leased
Premises; provided that Tenant shall not be required to deliver "as built" plans
and specifications in the event such Alterations are Decorative Alterations.
"Decorative Alterations" means any Alteration consisting of painting, wall
coverings, floor coverings, installation of cabinets, shelves or movable office
partitions or decorations (provided no approval by any Governmental Authority is
required). All plans and specifications delivered under this Lease shall be in a
form and format reasonably acceptable to Landlord.

      (f) Tenant shall indemnify and hold Landlord harmless from and against all
Losses, arising out of the acts or omissions of any Tenant Party in connection
with the construction of any Alteration, including any mechanics' or
materialmen's liens asserted in connection with such Alteration. Nothing in this
subsection shall be deemed or construed to limit Tenant's rights under Section
4.13.

      (g) All Alterations when made to the Leased Premises by Tenant, shall at
once become the property of Landlord and shall be surrendered to Landlord upon
termination of this Lease by lapse of time or otherwise; provided, however, this
clause shall not apply to movable equipment, removable trade fixtures, office
equipment or furniture and data fixtures and equipment owned by Tenant. Tenant
may install food, soft drink and other vending machines, pantries or cooking
equipment for the use of Tenant or its subtenants; provided, however, that
Tenant's installation of any cooking equipment or pantries shall be conditioned
on Tenant's satisfaction of and compliance with all applicable Legal
Requirements and all requirements imposed by any insurer of the Building or the
Project and Tenant's obtaining any required governmental permits and approvals;
provided, further, that with respect to any such cooking equipment or pantries,
Tenant shall be responsible for any additional cleaning and maintenance costs
incurred by reason thereof.

            (h) (i) Landlord shall not unreasonably withhold its consent to an
            Alteration consisting of the installation of a supplementary
            air-conditioning

                                       34
<PAGE>

            system to service the Leased Premises. Tenant's installation of such
            supplementary air-conditioning system shall comply with all other
            requirements of this Lease (including all other provisions of this
            Section 4.05). In connection with such installation, Tenant, at
            Tenant's sole cost and expense, may tap into the existing chilled
            water pipes of the Building to obtain chilled water for such
            supplementary system, subject to available capacity. Landlord shall
            furnish to such supplementary system chilled water at such times as
            Tenant shall request. Any installations required to connect Tenant's
            supplementary air-conditioning system to the chilled water pipes
            shall be made by Landlord at Tenant's expense.

                  (ii) Tenant shall pay Landlord, within 20 days after rendition
            of a bill therefor, for the supply of chilled water used by any
            supplementary air-conditioning system installed by Tenant under this
            Section, as measured by a clock or similar meter approved by
            Landlord and Tenant (provided that Tenant's approval shall not be
            unreasonably withheld) and installed, at Landlord's election, (1) by
            Landlord in coordination with Tenant's installation of the
            supplemental air-conditioning system or (2) by Tenant as part of the
            installation of its supplemental air-conditioning system using a
            contractor approved by Landlord. Tenant shall pay all costs related
            to the installation and all maintenance of such clock or meter. For
            all periods during which such clock or meters are not operational,
            Tenant shall pay to Landlord the Actual Cost of Tenant's consumption
            of chilled water by such supplemental air-conditioning system,
            provided that Landlord shall deliver to Tenant reasonable supporting
            documentation for such costs, sufficient to reasonably enable Tenant
            to confirm the same.

                  (iii) Tenant shall pay Landlord, within 20 days after
            rendition of a bill therefor, for all electricity consumed by any
            supplementary air-conditioning system installed by Tenant under this
            Section, as measured by a meter or meters approved by Landlord and
            Tenant (provided that Tenant's approval shall not be unreasonably
            withheld) and installed, at Landlord's election, (1) by Landlord in
            coordination with Tenant's installation of the supplemental
            air-conditioning system or (2) by Tenant as part of the installation
            of its supplemental air-conditioning system using a contractor
            approved by Landlord. Tenant shall pay all costs related to the
            installation and maintenance of such meters. For all periods during
            which such meters are not operational, Tenant shall pay an amount
            based upon Landlord's reasonable estimate of Tenant's consumption of
            electricity by such supplemental air-conditioning system, provided
            that Landlord shall deliver to Tenant reasonable supporting
            documentation for Landlord's calculation of such costs, sufficient
            to reasonably enable Tenant to confirm the basis of Landlord's
            calculations.

                  (iv) Tenant shall pay to Landlord for electricity under
            Section 4.05(b)(iii) an amount equal to 103% of (1) Landlord's
            Actual Costs for such electricity (which cost shall not include any
            administrative fee) plus (2) solely with respect to Landlord's
            Actual Cost for such electricity, any taxes or other

                                       35
<PAGE>

            charges related to such electricity (as applicable) or the supply
            thereof plus (3) any tax imposed upon Landlord's receipts from the
            sale or resale of electricity (as applicable) to Tenant, to the
            extent permitted to be reimbursed by applicable Legal Requirements.

      (i) Notwithstanding anything to the contrary contained in this Lease,
Tenant shall have no obligation to remove the existing vault and related
equipment located in the Leased Premises and/or any replacements or additions
thereto to the extent such replacements or additions do not increase the size
thereof (collectively, the "Vault"). Tenant may, at its election, either (a)
surrender the Vault at the end of the term of this Lease, in which case the same
shall become the property of Landlord, or (b) remove the Vault at or prior to
the end of the term of the Lease and repair any damage done to the Building as a
result of the removal of the Vault.

      (j) Landlord acknowledges that as of the date hereof Tenant owns and,
during the term of the Lease and any Renewal Term, shall continue to own,
operate, maintain and repair and have exclusive use of the existing chillers
located in the Building's central plant along with the existing loops and
distribution lines used in connection therewith and all related equipment and
improvements thereto (the "Tenant's Chillers") at no cost to Landlord; provided
that Tenant shall cooperate with Landlord in the transfer of NextiraOne, LLC
("Nextira") from Tenant's Chillers to another chiller system within the
Building, which transfer shall occur no later than October 1, 2004 (however
Landlord agrees that it shall use reasonable endeavors to complete such transfer
by June 1, 2004), and Tenant shall be responsible for any costs incurred in
connection with the capping off of Tenant's Chillers as a result of such
transfer; provided further that Landlord shall (i) reimburse Tenant for any
costs incurred by Tenant as a result of Nextira's use of Tenant's Chillers prior
to such transfer, which costs shall be based on Nextira's per ton actual
consumption of water and electricity and (ii) indemnify Tenant for any claims
brought by Nextira against Tenant (except to the extent caused by the gross
negligence or willful misconduct of Tenant, its agents or employees) as a result
of any failure of service or service disruption in connection with Nextira's use
of Tenant's Chillers. Tenant may, at its election, either (a) surrender Tenant's
Chillers at the end of the term of the Lease, in which case the same shall
become the property of Landlord, or (b) remove Tenant's Chillers at or prior to
the end of the term of this Lease and repair any damage to the Building
resulting from the removal of Tenant's Chillers.

      SECTION 4.06 LEGAL USE AND VIOLATIONS OF INSURANCE COVERAGE

      Tenant covenants and agrees with Landlord not to occupy or use the Leased
Premises, or permit any portion of the Leased Premises to be occupied or used,
for any business or purpose which is unlawful or deemed to be extra-hazardous on
account of fire, or permit anything to be done which would in any way increase
the rate of fire of liability or any other insurance coverage on the Building
and/or its contents, including the use, storage, disposal or transportation of
hazardous materials other than drinking cups, office supplies and similar
substances commonly

                                      36

<PAGE>

found in commercial office buildings in quantities or concentrations that do not
violate any Legal Requirement.

      Section 4.07 LAWS, REGULATIONS AND RULES OF THE BUILDING

      (a) Tenant covenants and agrees with Landlord to comply with all laws,
ordinances, orders, rulings, decisions, rules and regulations (state, federal,
municipal and other agencies or bodies having any jurisdiction thereof) relating
to the use, condition or occupancy of the Leased Premises (collectively "Legal
Requirements").

      (b) Tenant shall not cause or permit any "Hazardous Substance" (defined as
any chemical, pollutant, waste, compound or other substance in such forms,
concentrations, quantities or other conditions that are prohibited, regulated or
require assessment, monitoring, removal or remediation under any Legal
Requirement pertaining to health or the environment) to be used, installed,
stored, treated, generated, released or disposed on or in the Leased Premises or
any other portion of the Building or Project by Tenant, its partners, members,
shareholders, directors, officers, employees, subtenants, assignees, agents,
contractors, invitees and licensees (each a "Tenant Party" and collectively,
"Tenant Parties") of the Leased Premises. Tenant shall indemnify Landlord, its
partners, members, shareholders, directors, officers, employees, agents,
invitees and licensees (each a "Landlord Party" and collectively, "Landlord
Parties") for all costs and expenses incurred by Landlord to correct, or in any
manner related to, any violation by a Tenant Party of the covenant set forth in
the immediately preceding sentence, or to remove neutralize or render harmless
any Hazardous Substance resulting from a violation by Tenant of such covenant,
or to comply with the requirements of any regulatory body having jurisdiction
over Hazardous Substances, in connection with any such removal, or to contest
the actions of any such regulatory body with respect to the Leased Premises,
Building or Project as the result of any violation by any Tenant Party of such
covenant. Tenant's agreement to indemnify each Landlord Party shall survive the
expiration of this Lease. Tenant agrees that it will comply fully with all Legal
Requirements pertaining to health or the environment which apply to the Leased
Premises, Building or Project and the use and occupancy of the Leased Premises,
Building or Project. Nothing set forth in this subsection shall be deemed to
prevent Tenant's use of any Hazardous Substance customarily used in the ordinary
course of office work (including the operation of chillers, generators, UPS and
related equipment), provided such materials are used, handled, stored,
transported and disposed in accordance with all Legal Requirements.

      (c) Landlord shall comply with (or cause to be complied with), at its
expense, all Legal Requirements applicable to the common areas of the Project
which are not expressly the obligation of Tenant hereunder, to the extent that
non-compliance would materially impair Tenant's use and occupancy of the Leased
Premises and Tenant's ability to conduct its business in the Leased Premises for
the use intended hereby; provided, however, that Landlord may contest the
legality or applicability of any such Legal Requirement and may defer compliance
therewith during the pendency of such contest, so long as deferring compliance
does not unreasonably interfere with the conduct of Tenant's business.

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<PAGE>

      (d) Landlord shall, at its cost, perform all work to the restrooms
(excluding private restrooms) located within the Leased Premises to the extent
such work is necessary in order to comply with all applicable requirements of
the Americans with Disabilities Act, the Texas Architectural Barrier Act and the
rules and regulations promulgated in connection therewith (such work being
"Landlord's ADA Initial Work"). In connection with the foregoing, the parties
agree that Landlord's sole obligation shall be to assure that such restrooms
comply with all applicable requirements of the Americans with Disabilities Act,
the Texas Architectural Barrier Act and the rules and regulations promulgated in
connection therewith at the time such work is completed and that the foregoing
obligation shall not be deemed to impose upon Landlord any continuing obligation
in respect of work necessary to comply with the Americans with Disabilities Act,
the Texas Architectural Barrier Act and the rules and regulations promulgated in
connection therewith due to Alterations undertaken by Tenant or modifications to
the Americans with Disabilities Act, the Texas Architectural Barrier Act and the
rules and regulations promulgated in connection therewith enacted after
completion of Landlord's ADA Initial Work. In connection with its prosecution of
Landlord's ADA Initial Work, Landlord shall use reasonable efforts to minimize
any disruption of Tenant's conduct of its business at the Leased Premises.
Tenant shall, and shall cause each Tenant Party, to reasonably cooperate with
Landlord in connection with Landlord's prosecution of such work including
coordination of Landlord's prosecution of Landlord's ADA Initial Work with
Tenant's prosecution of Tenant's Initial Improvements. Tenant shall reimburse
Landlord for all increased costs incurred by Landlord in completing Landlord's
ADA Initial Work due to (1) any delay resulting from any act or omission of any
Tenant Party, including delays due to Tenant requested changes in or additions
to, or interference with Landlord's ADA Initial Work, or delays by Tenant in
submission of information requested by Landlord and necessary to complete such
work or (2) unique design features particular to Tenant's build-out of the
Leased Premises. Tenant shall promptly reimburse Landlord for such costs within
20 days after Tenant's receipt of Landlord's request for payment therefor.

      (e) Tenant and all Tenant Parties shall observe and comply with the
Building rules and regulations, provided that in case of any conflict or
inconsistency between the provisions of this Lease and any of the rules and
regulations as originally promulgated or as supplemented or amended from time to
time, the provisions of this Lease shall control. landlord reserves the right,
from time to time, to adopt additional rules and regulations and to amend the
rules and regulations then in effect, so long as none of the foregoing
materially and adversely affects Tenant's rights under this Lease or Tenant's
right of quiet enjoyment of the Leased Premises. Nothing contained in this Lease
shall impose upon Landlord any obligation to enforce the rules and regulations
or terms, covenants or conditions in any other lease against any other Building
tenant, and Landlord shall not be liable to Tenant for violation of the rules
and regulations by any other tenant, its employees, agents, visitors or
licensees, except that Landlord shall not enforce any Building rule or
regulation against Tenant in a discriminatory fashion.

      SECTION 4.08 ENTRY FOR REPAIR AND INSPECTION

      Upon reasonable prior notice to Tenant and at reasonable times (except
that such requirements shall not apply in the event of an emergency), Landlord
and Landlord's agents and

                                      38

<PAGE>

representatives shall be permitted entry upon any portion of the Leased Premises
deemed desirable by Landlord to inspect the same, clean or make repairs,
alterations or additions thereto, and Tenant shall not be entitled to any
abatement, setoff or reduction of Rent by reason thereof.

      SECTION 4.09 NUISANCE

      Tenant shall conduct its business in such manner so as not to create any
nuisance, or interfere with, annoy or disturb any other tenant or Landlord in
its operation of the Building. Tenant shall prevent each Tenant Party from
creating any nuisance, or interfering with, annoying or disturbing any other
tenant or Landlord in its operation of the Building. Tenant shall not, during
occupancy of, remodeling or construction within the Leased Premises, cause or
permit any strong, unusual, offensive or objectionable odors, gases or vapors to
be produced within the Leased Premises whether such odors, gases or vapors are
contained within the Leased Premises or migrate from or are permitted by Tenant
to be emitted outside of the Leased Premises. Landlord, in its sole discretion
exercised in good faith, shall determine if any such odors, gases or vapors are
in violation of this provision.

      SECTION 4.10 SUBORDINATION TO MORTGAGE; NON-DISTURBANCE

      (a) This Lease is subject and subordinate to any mortgage or deed of trust
(the "Underlying Mortgage") and each underlying master, financing or ground
lease (the "Underlying Lease") which may now or hereafter encumber all or any
part of Landlord's interest in the Project or Landlord's interest herein, and to
all renewals, modifications, consolidations, replacements and extensions
thereof, provided that such subordination shall only be effective if Tenant
receives a non-disturbance agreement from the holder of the subject Underlying
Mortgage (the "Mortgagee") or the lessor under the subject Underlying Lease (the
"Superior Lessor") (as applicable) satisfying the Non-Disturbance Requirements.
Tenant agrees however, a Mortgagee may at its option, unilaterally elect to
subordinate, by an instrument in form and substance satisfactory to such party,
such Underlying Mortgage to this Lease. In such case, Tenant agrees to execute
promptly and to deliver to Landlord or such party any such subordinate
instrument or instruments reasonably requested by such party and agrees that if
it fails or refuses to do so within 15 days after written request thereof by
Landlord or such party.

      (b) In the event of the enforcement by the Mortgagee of the remedies
provided for by law or by such Underlying Mortgage, or in the event of the
termination of an Underlying Lease, Tenant shall, upon request of any Person
succeeding to the interest of the Mortgagee or upon the request of the Superior
Lessor, automatically become the lessee of such successor in interest or such
lessor, as the case may be, without change in the terms or provisions of this
Lease; provided, that such successor in interest or lessor shall not be:

                  (i) bound by any payment of Rent for more than one month in
            advance of its due date, except prepayments in the nature of
            security for the performance by Tenant of its obligations under this
            Lease (but only to the extent such security is actually delivered to
            such successor in interest or such lessor);

                                      39

<PAGE>

                  (ii) bound by any amendment or modification of this Lease
            made without the consent of such successor in interest or lessor;

                  (iii) liable for any act or omission of the prior Landlord
            under this Lease, provided, however, that the foregoing shall not
            relieve such successor in interest or lessor from any obligation
            under this Lease with respect to an event or condition that
            continues (but only to the extent it continues) after the date such
            successor in interest or lessor succeeds to the interest of Landlord
            hereunder;

                  (iv) subject to any offset, deduction or defense which Tenant
            might have arising out of the acts or omissions of Landlord,
            provided, however, that the foregoing shall not relieve such
            successor in interest or lessor from any obligation under this Lease
            with respect to an event or condition that continues (but only to
            the extent it continues) after the date such successor in interest
            or lessor succeeds to the interest of Landlord hereunder; and

                  (v) bound by any covenant or obligation of Landlord to
            perform, undertake or complete any work in the Leased Premises or to
            prepare the Leased Premises for Tenant's occupancy or to make any
            payment in regard thereto.

      (c) As long as any Underlying Mortgage or Underlying Lease shall exist,
Tenant shall not seek to terminate this Lease by reason of any act or omission
of Landlord (i) until Tenant shall have given notice of such act or omission to
all Mortgagees and Superior Lessors, and (ii) until a reasonable period of time,
but not to exceed sixty (60) days, shall have elapsed following the giving of
notice of such default and the expiration of any applicable notice or grace
periods (unless such act or omission is not capable of being remedied within a
reasonable period of time) during which period such Mortgagees or Superior
Lessors (as applicable) shall have the right, but not the obligation, after
obtaining possession of the Project to remedy such act or omission and
thereafter diligently proceed to so remedy such act or obligation. If any
Mortgagee or Superior Lessor elects to remedy such act or omission of Landlord,
Tenant shall not seek to terminate this Lease so long as such Mortgagee or
Superior Lessor is proceeding with reasonable diligence to effect such remedy.

      (d) Landlord represents that, as of the date hereof, there are no existing
Underlying Mortgages or Underlying Leases.

      (e) The term "Non-Disturbance Requirements", with respect to a particular
Underlying Mortgage or Underlying Lease, means a non-disturbance agreement in
such Mortgagee's or Superior Lessor's (as applicable) customary form, provided
that such agreement (i) is reasonably acceptable to Tenant and (ii) provides
that the Mortgagee or Superior Lessor (as the case may be) agrees that (1)
Tenant's rights under this Lease and possession of the Leased Premises,
including parking, shall not be disturbed during the Term and (2) Tenant's
rights under this Lease shall not be terminated by such Mortgagee or Superior
Lessor (as the case may be), in

                                      40
<PAGE>

each case, so long as no Event of Default has occurred and continues beyond any
applicable notice or grace period.

      SECTION 4.11 ESTOPPEL CERTIFICATE

      (a) Within 15 days after request therefor by Landlord, Tenant shall
execute estoppel certificates addressed to the following Persons (as requested
by Landlord) (i) any Mortgagee or prospective Mortgagee of Landlord, (ii) any
Superior Lessor or prospective Superior Lessor, (iii) any purchaser or
prospective purchaser of all or any portion of, or interest in, the Building,
and (iv) any investor, or proposed investor, in the Building (directly or
indirectly), certifying to the best of Tenant's current, actual knowledge (after
reasonable inquiry):

            (1)   that this Lease is unmodified and in full force and effect (or
                  if there have been modifications, identifying such
                  modifications and certifying that the Lease, as modified, is
                  in full force and effect) and, if requested, certifying as to
                  a copy of this Lease, as it may have been amended;

            (2)   the dates to which all items of Rent has been paid;

            (3)   that the Landlord is not in default under any provision of
                  this Lease (or if the Landlord is in default, specifying each
                  such default);

            (4)   the address to which notices to Tenant shall be sent;

            (5)   whether Landlord has failed to complete any work required to
                  be performed by Landlord under this Lease;

            (6)   the Commencement Date, the Term and the Net Rentable Area of
                  the Leased Premises;

            (7)   whether Landlord has failed to complete any work required to
                  be performed by Landlord under this Lease;

            (8)   whether there are any subleases or assignments affecting the
                  Leased Premises; and

            (9)   other matters as such mortgagee(s), lessor(s), purchaser(s) or
                  investor may reasonably require.

      (b) Within 15 days after request therefor by Tenant, Landlord shall
execute an estoppel certificate addressed to (i) any Mortgagee or prospective
Mortgagee of Tenant, (ii) any assignee or subtenant or prospective assignee or
subtenant, or (iii) any purchaser or prospective purchaser of substantially all
of Tenant's assets or partnership units, certifying to Landlord's current,
actual knowledge (after reasonable inquiry):

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<PAGE>

            (1)   that this Lease is unmodified and in full force and effect (or
                  if there have been modifications, identifying such
                  modifications and certifying that the Lease, as modified, is
                  in full force and effect) and, if requested, certifying as to
                  a copy of this Lease, as it may have been amended;

            (2)   the dates to which all items of Rent have been paid;

            (3)   that Tenant is not in default under any provision of this
                  Lease (or if Tenant is in default, specifying each such
                  default);

            (4)   the address to which notices to Landlord shall be sent;

            (5)   the Commencement Date, the Term and the Net Rentable Area of
                  the Leased Premises; and

            (6)   other matters as such mortgagee(s), assignee, subtenant(s) or
                  transferee may reasonably require.

      SECTION 4.12 TENANT'S INITIAL IMPROVEMENTS

      Tenant shall (a) promptly cause all initial leasehold improvements (the
"Initial Improvements") in the Leased Premises to be constructed in accordance
with Schedule 4 and (b) deliver plans and specifications to Landlord relating to
the Initial Improvements in accordance with the terms, provisions and time
frames set forth in Schedule 4. Tenant shall substantially complete all Initial
Improvements to the extent applicable to the Contracted Portion of the Leased
Premises no later than the Contraction Date. Tenant shall bear the entire cost
of all Initial Improvements.

      SECTION 4.13 LIENS

      Tenant shall not be deemed to be the agent or representative of Landlord
in making any alterations, physical additions or improvements to the Leased
Premises, and shall have no right, power or authority to encumber any interest
in the Project in connection therewith. If any mechanics' or other liens are
filed against any portion of the Project or any interest therein by reason of
the acts or omissions of any Tenant Party or because of a claim against any
Tenant Party, Tenant shall cause the same to be cancelled or discharged of
record by bond or otherwise within 20 days after notice by Landlord. If Tenant
shall fail to cancel or discharge said lien or liens, within said 20-day period,
which failure shall be deemed to be a default hereunder, Landlord may, at its
sole option in addition to any other remedy of Landlord hereunder, cancel or
discharge the same and upon Landlord's demand, Tenant shall promptly reimburse
Landlord for all reasonable costs incurred in canceling or discharging such lien
or liens.

      SECTION 4.14 LIMITATION OF LANDLORD'S PERSONAL LIABILITY

      (a) Notwithstanding anything contained in this Lease to the contrary,
Landlord and Landlord's agents and employees shall not be liable to Tenant for
any injury to Person or damage

                                      42
<PAGE>

to property caused by the Leased Premises or other portions of the Building or
Project becoming out of repair, or by defect in or failure of equipment, pipes,
wiring, or broken glass, or by the backing up of drains, or by gas, water,
steam, electricity, or oil leaking, escaping or flowing into the Leased
Premises, except to the extent caused by the gross negligence or willful
misconduct of Landlord, its agents or employees, nor shall Landlord be liable to
Tenant for any loss or damage that may be occasioned by or through the acts or
omissions of other tenants of the Building or of any other Persons whomsoever.

      (b) It is expressly understood and agreed that notwithstanding anything in
this Lease to the contrary, the liability of Landlord hereunder (including any
successor landlord) and any recourse by Tenant against Landlord shall be limited
solely and exclusively to the interest of Landlord (and any successor Landlord)
in and to the Project (including the proceeds of any sale of all or part of the
Project and the proceeds of any applicable insurance), and the obligations of
Landlord under this Lease shall run with the land. No constituent partners,
members or owners of interests in Landlord or Landlord's or their respective
shareholders, members, directors or officers shall have any personal liability,
and Tenant hereby expressly waives and releases such personal liability on
behalf of itself and all Persons claiming by, through or under Tenant.

      SECTION 4.15 PARKING

      (a) Tenant shall be entitled to parking rights for the Minimum Number of
Parking Spaces in accordance with the terms of this Section 4.15. The Minimum
Number of Parking Spaces shall be adjusted, from time-to-time, to at all times
during the Term reflect 3 vehicles per 1,000 square feet of the Net Rentable
Area of the Leased Premises in order to take into account expansions and
contractions of the Net Rentable Area of the Leased Premises pursuant to the
terms of this Lease. Tenant may, at its election, allocate any portion or number
of Tenant's Minimum Number of Parking Spaces to any subtenants permitted
pursuant to Section 4.04 hereof, so long as any such subtenants comply with all
rules and regulations relating to the parking of vehicles then in effect.
Tenant's election to allocate any portion or number of the Minimum Number of
Parking Spaces as set forth in the preceding sentence shall not increase
Tenant's rights under Section 4.15(c) hereof.

      (b) The Minimum Number of Parking Spaces shall be located as follows: (i)
a number of spaces equal to 2 vehicles per 1,000 square feet of the Net Rentable
Area of the Leased Premises (such spaces being the "Garage Spaces") shall be
located in the Garage and (ii) a number of spaces equal to 1 vehicle per 1,000
square feet of the Net Rentable Area of the Leased Premises shall be located in
parking facilities located within the radius identified on Exhibit C.

      (c) Except as expressly provided otherwise in this Section 4.15(c), none
of the Garage Spaces will be assigned to Tenant, but Landlord will issue to
Tenant the applicable number of parking stickers, each of which will authorize
parking in the Garage of a vehicle on which the sticker is displayed, or
Landlord will provide a reasonable alternative means of identifying and
controlling vehicles authorized to park in the Garage. Landlord may designate
the area or areas of the Garage within which each such vehicle may be parked,
and Landlord may change such

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<PAGE>

designations from time to time. Landlord may make, modify and enforce rules and
regulations relating to the parking of vehicles in the Garage, and Tenant will
abide by and cause its agents, employees and invitees to comply with such rules
and regulations. Notwithstanding anything to the contrary in this Section
4.15(c), Tenant may elect, by written notice to Landlord of such election and
without additional cost, to have up to 10% of the Garage Spaces designated as
reserved parking spaces within the Garage for Tenant's exclusive use. In the
event Tenant makes such election, Landlord shall, within 60 days of Landlord's
receipt of Tenant's election, make available for Tenant's use the applicable
number of reserved parking spaces.

      (d) For so long as Transcontinental Gas Pipe Line Corporation or a Transco
Related Party shall be the tenant under this Lease there shall be no fee for the
Minimum Number of Parking Spaces.

      (e) Landlord shall provide parking for visitors to the Building in an area
designated by Landlord and in a capacity determined by Landlord to be
appropriate for the Project. Landlord reserves the right to charge and collect a
fee for parking in the visitor parking area in an amount determined by Landlord
to be appropriate. Landlord, at its sole discretion, may change the designated
area for the visitor parking and the fee to be charged for its use. For so long
as Transcontinental Gas Pipe Line Corporation or a Transco Related Party shall
be the tenant under this Lease, Tenant shall be permitted to purchase a
reasonable number of non-exclusive parking privileges for use by Tenant's
visitors for parking at the Garage. The cost of such privileges shall be 50% of
the cost customarily charged by Landlord (or the operator of the Garage, as
applicable) to third parties for such privileges (such discount shall not apply
to applicable taxes and other fees imposed by Governmental Authorities).

      (f) At Tenant's election and subject to availability, Landlord shall
provide up to 100 additional non-reserved parking spaces in an area reasonably
designated by Landlord. The cost of such privileges shall be 50% of the cost
customarily charged by Landlord (or the operator of the Garage, as applicable)
to third parties for such privileges (such discount shall not apply to
applicable taxes and other fees imposed by Governmental Authorities)

                                    ARTICLE 5
                      COVENANTS; MISCELLANEOUS PROVISIONS

      Landlord and Tenant mutually covenant and agree as follows:

      SECTION 5.01 CONDEMNATION

      (a) If the Leased Premises, any portion of the Project or any public
access to and from the Leased Premises shall be condemned or conveyed in lieu of
condemnation for any public purpose to such an extent as to render at least 50%
of the Leased Premises Untenantable, then:

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<PAGE>

                  (i) Tenant may terminate this Lease by notice to Landlord of
            such election delivered within 120 days after the date upon which
            Tenant receives written notice of such acquisition or condemnation;
            and

                  (ii) Landlord may terminate this Lease by notice to Tenant of
            such election delivered within 120 days after the date upon which
            Landlord receives written notice of such acquisition or
            condemnation, provided that Landlord also elects to terminate leases
            at the Building (including this Lease) affecting at least 75% of the
            portion of the Net Rentable Area of the Building that is subject to
            such condemnation or acquisition (excluding any Net Rentable Area
            leased by Landlord or its Affiliates).

      In addition to the foregoing, Tenant may terminate this Lease by notice to
      Landlord of such election delivered within 120 days after the date upon
      which Tenant receives written notice of such acquisition or condemnation
      if the same will materially deny Tenant's ability to use the Minimum
      Number of Parking Spaces, unless Landlord designates reasonably comparable
      substitute parking spaces within 10 Business Days after Landlord's receipt
      of Tenant's termination notice. If Landlord designates such substitute
      parking spaces within such 10-Business Day period, then Tenant's
      termination notice shall be rendered null and void.

      (b) All proceeds from any taking or condemnation of the Leased Premises or
any other portion of the Project shall belong to and be paid to Landlord. Tenant
shall be permitted to make a separate claim in any condemnation proceeding for
the then value of any Tenant's property or Alterations (in each case, only to
the extent Tenant has paid for such items) included in such taking and for any
moving expenses, provided any such award is in addition to, and does not result
in a reduction of, the award made to Landlord.

      (c) The term "Untenantable" means a condition whereby Tenant is not
reasonably able to use the Leased Premises or a portion thereof for the conduct
of its business in accordance with its customary practices, provided that it
shall be an express condition to untenantability that Tenant does in fact not
use the portion of the Leased Premises purported to be untenantable for the
conduct of its business (provided, that, entering such portion of the Leased
Premises for the purpose of retrieving documents or other personal property or
otherwise in connection with the relocation of Tenant's operations therein to
other space shall not be deemed to constitute use of such space for the purposes
of this paragraph).

      SECTION 5.02 DAMAGES FROM CERTAIN CAUSES

      Landlord shall not be liable or responsible to Tenant for any loss or
damage to any property or person occasioned by theft, fire, act of God, public
enemy, act of terrorism, injunction, riot, strike, insurrection, war, court
order, requisition or order of Governmental Authority, or any cause beyond
Landlord's reasonable control, or for any other damage (except to the extent
caused by the gross negligence or willful misconduct of Landlord, its agents or

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<PAGE>

employees) or inconvenience which may arise through repair or alteration of any
part of the Building, or failure to make any such repairs.

      SECTION 5.03 WAIVER OF LANDLORD'S LIEN

      Landlord shall have no lien (whether contractual or statutory) on, or
security interest in, any of Tenant's removable personal property (including
furniture, trade fixtures and equipment) located in, on or about the Leased
Premises or the Project, and Landlord hereby expressly waives and releases any
such lien or security interest it may have in such property.

      SECTION 5.04 LANDLORD'S RIGHT TO RELET

      Upon the occurrence of an Event of Default, Landlord shall have the right,
but not the obligation, except to the extent required by law, to mitigate its
damages or relet same for the remainder of the Term, and if the rent received
through reletting does not at least equal the Rent provided for herein, Tenant
shall pay and satisfy the deficiency between the amount of the Rent provided for
hereunder and that received through reletting, including, but not limited to,
the cost of reletting and related commissions, renovating, altering and
decorating for a new occupant; provided, however, that if the new lease has a
term that extends beyond the then remaining term of this Lease (not including
any unexercised renewal or extension terms), Tenant shall only bear an
appropriate share of such amounts taking into account, among other things, the
term of the new lease versus the remaining term of this Lease and any deficiency
between the amount of rent payable under the new lease and the Rent payable
under this Lease. Nothing herein shall be construed as in any way denying
Landlord the right, upon the occurrence of an Event of Default by Tenant, to
treat the same as a material breach and at Landlord's option to terminate this
Lease and/or immediately seek recovery for the entire breach of this Lease and
any and all damages which Landlord suffers thereby.

      SECTION 5.05 HOLDING OVER

      In the event of holding over by Tenant after expiration or termination of
this Lease without the written consent of Landlord, Tenant shall pay as
liquidated damages for any month (or any portion thereof) during which Tenant
holds over in the Leased Premises after the expiration date or sooner
termination of the Term, a sum equal to 150% of the Rent payable under this
Lease for the last full calendar month of the Term. No holding over by Tenant
after the Term shall be construed to extend this Lease; in the event of any
unauthorized holding over, Tenant shall (a) be liable to Landlord for (i) any
payment or rent concession which Landlord may be required to make to any tenant
obtained by Landlord for all or any part of the Leased Premises (a "New Tenant")
in order to induce such New Tenant not to terminate its lease by reason of the
holding over by Tenant, (ii) any postponement of rent that any New Tenant may be
entitled to under the under the terms of any lease with such New Tenant by
reason of Tenant holding over beyond the Term and (iii) the loss of the benefit
of the bargain if any New Tenant shall terminate its lease by reason of Tenant
holding over beyond the Term, and (b) indemnify Landlord against

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<PAGE>

all claims for damages by any New Tenant. Any holding over with the consent of
Landlord in writing shall thereafter constitute this Lease a lease from month to
month.

      SECTION 5.06 FIRE OR OTHER CASUALTY CLAUSE

      (a) In the event of a fire or other casualty to the Leased Premises,
Tenant shall promptly give notice thereof to Landlord. If the Leased Premises or
the Project (or any portion of any of the foregoing) shall be partially or
totally destroyed by fire or other casualty so as to render any portion of the
Leased Premises Untenantable (a "Casualty Condition"), the Rent provided for
herein shall abate with respect to the portion of the Premises rendered
Untenantable for the period commencing on the date of such Casualty Condition
until the date upon which the affected portion of Leased Premises is rendered no
longer Untenantable.

      (b) In the event of a Casualty Condition, Landlord shall notify Tenant of
the date by which Landlord's architect or contractor reasonably and in good
faith estimates the restoration of the Leased Premises shall be substantially
completed (such notice being the "Restoration Notice"). Landlord shall deliver
to Tenant the Restoration Notice upon the earlier to occur of (i) 90 days after
the date of such Casualty Condition and (ii) 20 days after the date on which
Landlord receives notice from the last applicable Mortgagee and Superior Lessor
to provide notice to Landlord of such Mortgagee's or Superior Lessor's
instructions regarding restoration (if any such rights exist).

      (c) In the event of a Casualty Condition, and if restoration cannot be
substantially completed within 180 days after the date of such Casualty
Condition (as reasonably determined by Landlord or Landlord's architect or
contractor), then, in each case,

                  (i) Tenant may terminate this Lease by notice to Landlord of
            such election delivered within 30 days after the date upon which
            Tenant receives the Restoration Notice; and

                  (ii) Landlord may terminate this Lease by notice to Tenant of
            such election delivered within 30 days after the date of the
            Restoration Notice, provided that Landlord also elects to terminate
            leases at the Building (including this Lease) affecting at least 75%
            of the portion of the Net Rentable Area of the Building that is
            affected by such casualty (excluding any Net Rentable Area leased by
            Landlord or its Affiliates).

      If this Lease is so terminated, the Term shall expire upon the date set
      forth in Tenant's or Landlord's (as the case may be) notice, which shall
      not be less than 30 days after such notice is given, and Tenant shall
      vacate the Leased Premises and surrender the same to Landlord in the
      condition required hereby (except to the extent such Casualty Condition
      makes it unfeasible to do so, in which case the Leased Premises shall be
      returned in its then current condition to such extent) no later than the
      date set forth in the notice.

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<PAGE>

      (d) In the event of a Casualty Condition and such restoration can be
substantially completed within 180 days after the date of such Casualty
Condition (as reasonably determined by Landlord or Landlord's architect or
contractor) (or this Lease is not terminated by either party under Section
5.06(c)), Landlord shall, subject to the provisions of any applicable Mortgage
or Superior Lease, at Landlord's expense, repair the Leased Premises and the
Project (as applicable) to substantially the condition existing immediately
prior to such damage, provided that (i) Landlord shall have no obligation to
repair or restore any (1) Tenant's property or (2) any specialty Alterations.
Until such time as the restoration of the Leased Premises is substantially
completed or would have been substantially completed but for any delay caused by
any Tenant Party, Rent shall abate in accordance with the provisions of Section
5.06(a) commencing on the date of such Casualty Condition.

      (e) If Landlord decides, or is required, to restore the Leased Premises
hereunder, Landlord shall commence and prosecute any repair work promptly and
with reasonable diligence but shall only be obligated to restore or rebuild the
Leased Premises to Building standard condition (including completion of
Landlord's ADA Initial Work).

      (f) Notwithstanding anything set forth to the contrary in this Section
506 and in addition to the rights set forth in Section 5.06(c), Tenant may also
terminate this Lease by notice to Landlord of such election delivered no later
than 30 days after the date upon which Tenant receives the Restoration Notice if
(i) a Casualty Condition occurs during the final 12 months of the Term (after
giving effect to all Renewal Terms exercised by Tenant) and (ii) the Leased
Premises cannot be substantially completed within 60 days after the date of such
Casualty Condition (as reasonably determined by Landlord or Landlord's architect
or contractor). In the event Tenant elects to terminate this Lease in accordance
with the foregoing, this Lease shall expire on the 30th day after Tenant's
delivery of its such termination notice.

      SECTION 5.07 ATTORNEY'S FEE

      (a) In the event Tenant defaults in the performance of any of the terms,
covenants, agreements or conditions contained in this Lease and Landlord places
the enforcement of this Lease, or any part thereof, or the collection of any
rent due, or to become due hereunder or recovery of the possession of the Leased
Premises in the hands of an attorney, or files suit upon the same, Tenant agrees
to pay Landlord's reasonable attorney's fees.

      (b) In the event Landlord fails to perform any of its obligations
contained in this Lease and Tenant is required to commence litigation to obtain
such performance, Landlord agrees to pay Tenant's reasonable attorney's fees in
the event and to the extent Tenant prevails in such litigation.

      SECTION 5.08 AMENDMENTS

      This Lease may not be altered, changed or amended, except by an instrument
in writing signed by both parties hereto.

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<PAGE>

      SECTION 5.09 ASSIGNMENT BY LANDLORD

      Landlord shall have the right to transfer and assign, in whole or in part,
all its rights and obligations hereunder and in the Building and property
referred to herein, and in such event and upon such transfer to a transferee or
assignee who assumes pursuant to a written agreement Landlord's obligations
under this Lease to the extent accruing on or after the date of such transfer or
assignment (any such transferee to have the benefit of, and be subject to, the
provisions of Section 4.14) no further liability or obligation shall thereafter
accrue against Landlord hereunder or under any agreement relating to this Lease.

      SECTION 5.10 DEFAULT BY TENANT

      (a) The occurrence of each of the following shall be deemed an "Event of
Default" hereunder:

                  (i) if Tenant shall fail to pay when due any installment of
            (i) Base Annual Rental or Base Rooftop Rental Rent and such failure
            continues for 5 days after Landlord's delivery to Tenant of notice
            of such non-payment or (ii) Additional Rent and such failure
            continues for 10 days after Landlord's delivery to Tenant of notice
            of such non-payment; except that, in each case, in no event shall
            Landlord be required to provide such notice and opportunity to cure
            with respect to more than three (3) such defaults during any
            12-month period; or

                  (ii) if Tenant shall default in the performance of any of the
            other covenants or conditions not covered by other clauses in this
            Section 5.10 which Tenant is required to observe and to perform, and
            such default shall continue for 30 days after written notice thereof
            given by Landlord to Tenant (which such notice shall specify in
            reasonable detail the nature of such default); provided, however, if
            the nature of the default is such that it cannot be cured with the
            exercise of commercially reasonable efforts within such 30-day
            period, then (1) Tenant shall have up to 90 days from the date of
            Landlord's notice to cure such default, provided that Tenant
            commences such curative action within the initial 30-day period and,
            thereafter, diligently and continuously proceeds with such curative
            action using commercially reasonable efforts to so cure such default
            and (2) subject to the requirements of this subsection, it shall not
            be deemed an Event of Default hereunder until such additional time
            has elapsed; or

                  (iii) if Tenant's interest under this Lease shall be levied
            upon pursuant to execution or other legal process, or if any
            petition shall be filed by or against Tenant to declare Tenant a
            bankrupt or to delay, reduce or modify Tenant's debts or
            obligations, or if any petition shall be filed or other action taken
            to reorganize or modify Tenant's capital structure if Tenant be a
            corporation or other entity and such proceeding is not dismissed or
            set aside within 60 days after the date of filing

                                      49

<PAGE>

            (except that such 60-day cure period shall not apply if such filing
            is made by Tenant or any Affiliate of Tenant); or

                  (iv) if Tenant shall be declared insolvent according to law;
            or

                  (v) if Tenant is a corporation, limited partnership or limited
            liability company and Tenant shall cease to exist as a corporation
            in good standing under either the laws of the State of Texas or the
            state of its formation or if Tenant is a partnership or other entity
            and shall be dissolved or otherwise liquidated; or

                  (vi) if Tenant files a voluntary petition in bankruptcy or
            insolvency, or is adjudicated a bankrupt or insolvent, or files any
            petition or answer seeking any reorganization, liquidation,
            dissolution or similar relief under any present or future federal
            bankruptcy act or any other present or future applicable Legal
            Requirements, or makes an assignment for the benefit of creditors or
            seeks or consents to or acquiesces in the appointment of any
            trustee, receiver, liquidator or other similar official for Tenant
            or for all or any part of Tenant's property, or

                  (vii) if, (1) within 90 days after the commencement of any
            proceeding against Tenant, whether by the filing of a petition or
            otherwise, seeking bankruptcy, insolvency, reorganization,
            arrangement, composition, readjustment, liquidation, dissolution or
            similar relief under the present or any future federal bankruptcy
            act or any other present or future applicable Legal Requirements,
            such proceeding shall not have been dismissed, or (2) within 90 days
            after the appointment of any trustee, receiver, liquidator or other
            similar official for Tenant or for all or any part of Tenant's
            property, without the consent or acquiescence of Tenant, such
            appointment shall not have been vacated or otherwise discharged, or
            (3) subject to Section 4.13. any lien, execution or attachment or
            other similar filing shall be made or issued against Tenant or any
            of Tenant's property pursuant to which the Leased Premises shall be
            taken or occupied or attempted to be taken or occupied by someone
            other than Tenant; or

                  (viii) if Tenant shall timely fail to deliver any document
            required by Section 4.10 or 4.11.

      (b) Upon the occurrence of an Event of Default, Landlord, at Landlord's
option, may pursue any one or more of the following described remedies in
addition to all other rights and remedies available at law or in equity:

                  (i) Landlord may terminate this Lease and forthwith repossess
            the Leased Premises and be entitled to recover forthwith as damages
            a sum of money equal to the total of (1) the cost of recovering the
            Leased Premises, (2) the unpaid Rent earned at the time of
            termination, plus interest thereon at the maximum non-usurious rate
            per annum from the due date until paid, (3) the present value of the
            balance of the Rent for the remainder of the Term (discounted at 6%
            per annum)

                                      50

<PAGE>

            less the fair market rental value of the Leased Premises for said
            period and (4) any other sum of money and damages owed by Tenant to
            Landlord.

                  (ii) Landlord may terminate Tenant's right of possession (but
            not this Lease) and may repossess the Leased Premises by forcible
            entry of detainer suit or otherwise, without demand or notice of any
            kind to Tenant and without terminating this Lease, in which event
            Landlord may, but shall be under no obligation to do so, relet the
            same for the account of Tenant for such rent and upon such terms as
            shall be satisfactory to Landlord. For the purpose of such reletting
            Landlord is authorized to decorate or to make any repairs, changes,
            alterations or additions in or to the Leased Premises that may be
            necessary or convenient, and (1) if Landlord shall fail to relet the
            Leased Premises, or (2) if the same are relet and a sufficient sum
            shall not be realized from such reletting after paying the unpaid
            Rent due hereunder plus interest at the maximum non-usurious rate
            thereon, the cost of recovering possession, and all of the costs and
            expenses of such decorations, repairs, changes, alterations and
            additions and the expense of such reletting (provided, however, that
            if the new lease has a term that extends beyond the then remaining
            term of this Lease (not including any unexercised renewal or
            extension terms), Tenant shall only bear an appropriate share of
            such amounts taking into account, among other things, the term of
            the new lease versus the remaining term of this Lease and any
            deficiency between the amount of rent payable under the new lease
            and the Rent payable under this Lease) and of the collection of the
            rent accruing therefrom to satisfy the rent provided for in this
            Lease to be paid, then Tenant shall pay to Landlord as damages a sum
            equal to the amount of the rental reserved in this Lease for such
            period or periods, or if the Leased Premises have been relet, the
            Tenant shall satisfy and pay any such deficiency upon demand
            therefor from time to time and Tenant agrees that Landlord may file
            suit to recover any sums falling due under the terms of this Section
            5.10(b) from time to time, and that no delivery to or recovery of
            any portion due Landlord hereunder shall be any defense in any
            action to recover any amount not theretofore reduced to judgment in
            favor of Landlord, nor shall such reletting be construed as an
            election on the part of Landlord to terminate this Lease unless a
            written notice of such intention be given to Tenant by Landlord.
            Notwithstanding any such reletting without termination, Landlord may
            at any time thereafter elect to terminate this Lease for such
            previous breach.

                  (iii) Landlord or Landlord's agent may change the door locks
            of the Leased Premises. In such event, Landlord or its agent shall
            place a written notice on Tenant's front door stating the name and
            address or telephone number of the individual or company from which
            a new key may be obtained. The key may be obtained (1) only during
            Landlord's regular business hours and (2) only upon payment in full
            of all delinquent Rent. Landlord may lock out Tenant in the event of
            any such default without being deemed in any manner guilty of
            conversion, trespass, eviction, or forcible entry or detainer;
            without incurring any liability for

                                      51

<PAGE>

            any damage, claim or cause of action resulting therefrom; and
            without relinquishing any other right or rights given to Landlord
            hereunder or by operation of law or in equity. If Landlord shall
            violate the provisions of this subparagraph, Tenant's sole remedy
            shall be to recover possession of the Leased Premises and Tenant
            expressly waives any and all rights and remedies under Section
            93.002(g) of the Texas Property Code, as amended. As expressly
            provided in Section 93.002(h) of the Texas Property Code, the terms
            and conditions of this subparagraph of the Lease supersede the
            provisions of said Section 93.002 to the extent of any conflict
            between the two provisions.

      SECTION 5.10A. TENANT'S REMEDIES FOR LANDLORD'S FAILURE TO PERFORM

            Except as otherwise provided or limited herein, Tenant shall be
entitled to pursue any remedies it has in law or in equity for Landlord's
failure to perform its obligations hereunder.

      SECTION 5.11 NON-WAIVER

      (a) Failure of Landlord to declare any default immediately upon occurrence
thereof, or delay in taking any action in connection therewith, shall not waive
such default, but Landlord shall have the right to declare any such default at
any time and take such action as might be lawful or authorized hereunder, either
in law or in equity.

      (b) Failure of Tenant to assert any failure of Landlord to perform any of
Landlord's obligations under this Lease immediately upon the occurrence thereof,
or delay in taking any action in connection therewith, shall not waive Tenant's
rights in respect thereof, but Tenant shall have the right to assert such
failure by Landlord at any time and take such action as might be lawful or
authorized hereunder, either in law or in equity.

      SECTION 5.12 CASUALTY INSURANCE OF LANDLORD

      (a) Landlord shall maintain, or cause to be maintained, at Landlord's
expense (subject to inclusion as an Operating Expense as provided below) a
policy or policies of insurance with premiums thereon fully paid in advance,
insuring the Project and the building standard improvements against loss or
damage by fire or other insurable hazards and contingencies for the full
insurable value thereof, or, in the alternative, at Landlord's election,
insuring for 80% of the replacement cost thereof (or such greater or lesser
amount as shall be required to eliminate operation of coinsurance provisions),
exclusive of excavations and foundations; provided, however, that Landlord shall
not be obligated to insure any furniture, equipment, machinery, goods or
supplies not covered by this Lease and Tenant may keep or maintain in the Leased
Premises, or any non-building standard leasehold improvements or alterations
that Tenant may make upon the Leased Premises. If the annual premiums charged
Landlord for such casualty insurance exceed the standard premium rates because
the nature of Tenant's operations result in extra-hazardous or higher than
normal risk exposure, then Tenant shall, upon receipt of appropriate premium
invoices and reasonable supporting documentation, reimburse Landlord for such
increases in premium. Any payments for losses under Landlord's casualty
insurance shall

                                      52

<PAGE>

be made solely to Landlord (subject to the rights of all applicable Mortgagees
and Superior Lessors).

      (b) Landlord (with respect to the Project) shall maintain or cause to be
maintained a policy or policies of comprehensive general liability or commercial
liability insurance with premiums paid thereon fully paid in advance. Such
insurance shall afford minimum protection of not less than $1,000,000 for bodily
injury, or death in any one occurrence and not less than $250,000 for property
damage in any one occurrence and shall include such coverages and endorsements
as Landlord may desire.

      (c) All insurance proceeds payable under Landlord's insurance carried
pursuant to this Lease or otherwise shall be payable solely to Landlord, and
Tenant shall have no interest therein. The expense for all Landlord's insurance
will be an Operating Expense under Section 2.05 of this Lease. If the annual
premiums charged Landlord for such casualty insurance exceed the standard
premium rates because the nature of Tenant's operations results in
extra-hazardous or higher than normal risk exposure, then Tenant shall, upon
receipt of appropriate premium invoices, reimburse Landlord for such increases
in premium which shall be a portion of Tenant's additional rental. Upon request
of Tenant, Landlord shall provide Tenant reasonable evidence that the insurance
required to be maintained hereunder by Landlord is in full force and effect.

      (d) All policies required to be carried by Landlord under this Section
5.12. shall be written with financially responsible insurance companies
authorized to do business and licensed in Texas having a Best's Insurance Guide
(or any successor thereto (or if there be none, an organization having a
national reputation)) Rating of "A-" and a "Financial Size Category" of at least
"VIII" or, if such ratings are not then in effect, the equivalent thereof.

      SECTION 5.13 TENANT'S INSURANCE

      (a) Tenant shall provide insurance coverage during the Term against loss
or damage by fire, other casualty and such other risks (including, but not
limited to sprinkler leakage and water damage) as are from time to time included
in a standard "all risks" policies for any leasehold improvements, any
alterations, Tenant's trade fixtures, furnishings, equipment, and all other
items of personal property of Tenant, insuring the full replacement cost or full
insurable value thereof, with a deductible not to exceed $2,000,000.

      (b) Tenant shall also maintain (i) worker's compensation, if Tenant is a
subscriber thereto or if such insurance is otherwise required to comply with
Tenant's obligations to its employees under the law in Texas; and (ii)
employer's liability insurance with limits of not less than $500,000 per
accident, $500,000 per employee for bodily injury by disease and $500,000 policy
limit for bodily injury by disease.

      (c) Tenant (with respect to the Leased Premises and Project) shall
maintain or cause to be maintained a policy or policies of commercial liability
insurance with (i) contractual liability covering the indemnification provisions
contained in this Lease, (ii) broad form property damage liability, and (iii) a
severability of interest endorsement. Such policy or policies shall

                                      53

<PAGE>

have limits of not less than $1,000,000 combined single limit per occurrence and
not less than $2,000,000 in the aggregate for bodily injury, sickness or death,
and property damage and umbrella coverage or excess liability insurance of not
less than $3,000,000 involving or arising out of use, occupancy, maintenance or
condition of the Leased Premises, Building or Project or Tenant's operations,
the premiums thereon fully paid in advance. Any general aggregate limit shall
apply on a per location basis.

      (d) Tenant shall cause each contractor and subcontractor performing work,
on Tenant's behalf, on the Leased Premises to maintain insurance as follows,
with such other terms, coverages and insurers, as Landlord shall reasonably
require from time to time:

                  (i) Commercial General Liability Insurance, including coverage
            for contractual liability, completed operations coverage and broad
            form property damage endorsement, to afford protection with limits,
            for each occurrence, of not less than $1,000,000 with respect to
            personal injury, death or property damage.

                  (ii) Worker's compensation or similar insurance in form and
            amounts required by law, and Employer's Liability with not less than
            the following limits:

<TABLE>
<S>                        <C>
Each Accident              $500,000

Disease-Policy Limit       $500,000

Disease-Each Employee      $500,000
</TABLE>

                  (iii) Builder's risk in amounts at least equal to the full
            value of or cost of the work being done by such contractor.

Such insurance shall contain a waiver of subrogation provision in favor of
Landlord, Tenant and all other Additional Insured Parties. Such contractor's
insurance shall be primary and not contributory to that carried by Tenant,
Landlord and all other Additional Insured Parties. Tenant and Landlord shall
each be named as additional insured on such contractor's insurance policies,
with the exception of the policy providing workers' compensation insurance.
Tenant shall deliver, or cause to be delivered, to Landlord certificates
evidencing all required insurance under this subsection (d) no later than five
(5) days prior to the start of any work. Each certificate will provide that the
applicable insurance company shall provide 20 days' prior written notice to
Tenant, Landlord and all other Additional Insured Parties prior to any
cancellation or material modification of such insurance policies. Tenant agrees
that Tenant shall not permit any contractor or subcontractor to perform work on
the Leased Premises without current evidence of such coverage and Tenant shall
be solely responsible for monitoring the insurance for compliance with this
Section. Dependent upon the scope of work to be performed at the Leased
Premises, Landlord has the right to require increased limits or broader
coverages as Landlord reasonably deems appropriate.

                                      54

<PAGE>

      (e) All policies required to be carried by Tenant under this Section 5.13,
shall be written with financially responsible insurance companies authorized to
do business and licensed in Texas having a Best's Insurance Guide (or any
successor thereto (or if there be none, an organization having a national
reputation)) Rating of "A-" and a "Financial Size Category" of at least "VIII"
or, if such ratings are not then in effect, the equivalent thereof.

      (f) All evidence of insurance provided to Landlord shall provide (i)
evidence satisfactory to Landlord that Landlord, Landlord's property manager,
all Superior Lessors, all Mortgagees and any other parties whose names shall
have been furnished by Landlord to Tenant from time to time and each of their
respective partners, shareholders, members, officers, directors, agents and
employees (the foregoing parties are collectively referred to herein as the
"Additional Insured Parties") are each named as additional insureds (except to
the extent not available in respect of worker's compensation insurance), but
only to the extent of Tenant's obligations, liabilities and indemnities under
this Lease, and where applicable loss payee and (ii) an endorsement whereby the
insurer agrees not to cancel or alter the policy without at least 30 days' prior
written notice to Landlord and all other Additional Insured Parties. Any
deductible or self-insurance provisions under any insurance policies maintained
by Tenant shall be subject to Landlord's prior written approval, which shall not
be unreasonably withheld.

      (g) If Tenant fails to provide evidence of insurance required by this
Lease, prior to commencement of the Term, and at any time during the Term,
within 15 days prior to the expiration date of any such coverage, Landlord shall
be authorized (but not required) to procure such coverage in the amounts stated
with all costs thereof to be charged to Tenant and paid upon written invoice
therefor as Additional Rent.

      (h) The certificates evidencing Tenant's insurance required under this
Lease (which Tenant shall provide to Landlord prior to the Commencement Date or
the expiration date of such particular coverage, as applicable) shall state that
(i) to the extent covered by the particular policy (nothing herein being
intended to limit Tenant's obligations to provide such insurance hereunder), the
insurance includes the liability assumed by Tenant under this Lease, (ii)
Tenant's insurance is primary and that any other insurance available to Landlord
or any other of the Additional Insured Parties is excess coverage, but only to
the extent of Tenant's obligations, liabilities and indemnities under this
Lease, (iii) Landlord and all other Additional Insured Parties are each an
additional insured, but only to the extent of Tenant's obligations, liabilities
and indemnities under this Lease and where applicable loss payee, and (iv)
Landlord and each other Additional Insured Party shall receive written notice
from the insurance company 30 days prior to any cancellation or material
modification of such policy.

      SECTION 5.14 INDEMNITY; HOLD HARMLESS

      (a) Landlord shall not be liable to any Tenant Party for any injury or
damage to person or property caused by any act, omission or negligence of any
Tenant Party or any other person entering the Project under the express or
implied invitation of Tenant, or arising out of the

                                      55
<PAGE>

use of the Leased Premises by Tenant on the conduct of its business thereon, or
arising out of any breach or default by Tenant in the performance of any of its
obligations under this Lease.

      (b) Tenant shall indemnify, defend, protect and hold harmless all Landlord
Parties, Mortgagees and Superior Lessors and each of their respective partners,
shareholders, members, officers, directors, employees, agents (including
managers) (collectively, "Indemnitees") from and against any and all Losses,
resulting from any claims (i) against the Indemnitees arising from any act,
omission or negligence of any Tenant Party or any accident, injury or damage
whatsoever in or about the Leased Premises (except to the extent caused by or
arising out of the negligence or willful misconduct of Landlord, Landlord's
agents or employees or any of the Indemnitees) caused to any Person or to the
property of any Person and occurring during the Term or during the period of
time, if any, prior to the commencement or following the expiration of the Term
that any Tenant Party may have been given access to any portion of the Leased '
Premises for the purpose of performing work or otherwise, in or about the Leased
Premises and (ii) against the Indemnitees resulting from any breach, violation
or nonperformance by Tenant of any covenant, condition or agreement of this
Lease (including any breach by Tenant of Section 1.07 or Section 1.08).

      (c) Landlord shall indemnify, defend, protect and hold harmless Tenant and
its partners, members, shareholders, directors, officers and employees
(collectively, "Tenant Indemnity Parties" from and against any and all Losses,
resulting from any claims:

                  (i) against the Tenant Indemnity Parties arising from any act,
            omission or negligence of any Landlord Party or any accident, injury
            or damage whatsoever in or about the Project (except to the extent
            caused by or arising out of the willful misconduct or negligence of
            any Tenant Party) caused to any Person or to the property of any
            Person and occurring during the Term; and

                  (ii) against the Tenant Indemnity Parties resulting from any
            breach, violation or nonperformance by Landlord of any covenant,
            condition or agreement of this Lease (except that in no event shall
            Landlord be liable for any consequential or other special damages).

      (d) The term "Losses" means any and all losses, liabilities, damages,
claims, judgments, fines, suits, demands, costs, interest and expenses of any
kind or nature (including reasonable attorneys' fees and disbursements) incurred
in connection with any claim, proceeding or judgment and the defense thereof,
and including all costs of repairing any damage to the Leased Premises or the
Project or the appurtenances of any of the foregoing to which a particular
indemnity and hold harmless agreement applies.

      (e) Tenant shall not be liable to any Landlord Party for any Loss caused
by any act, omission or negligence of any Landlord Party or arising out of any
breach or default by Landlord in the performance of any of its obligations under
this Lease.

                                       56
<PAGE>

      (f) Tenant agrees that Tenant shall contractually require all contractors
and subcontractors doing any work or activity relating to or in connection with
the Leased Premises to indemnify and hold harmless all Landlord Parties under
the terms of the indemnity set forth in Section 5.14 (b)

      SECTION 5.15 WAIVER OF SUBROGATION RIGHTS

      NOTWITHSTANDING ANYTHING IN THIS LEASE TO THE CONTRARY, EACH PARTY HEREBY
WAIVES ANY AND ALL RIGHTS OF RECOVERY, CLAIM, ACTION OR CAUSE OF ACTION, AGAINST
THE OTHER PARTY OR ANY OF THEIR RESPECTIVE PARTNERS, SHAREHOLDERS, MEMBERS,
OFFICERS, DIRECTORS, AGENTS OR EMPLOYEES, FOR ANY LOSS OR DAMAGE THAT MAY OCCUR
OR RELATE TO THE LEASED PREMISES, OR ANY IMPROVEMENTS THERETO, OR SAID BUILDING
OR PROJECT, OR ANY IMPROVEMENTS THERETO, OR ANY PERSONAL PROPERTY OF SUCH PARTY
THEREIN, BY REASON OF FIRE, THE ELEMENTS, ANY OTHER CASUALTY OR ANY OTHER CAUSE
WHICH ARE REQUIRED TO BE INSURED AGAINST UNDER THE TERMS OF STANDARD FIRE AND
EXTENDED COVERAGE INSURANCE POLICIES REQUIRED BY SECTION 5.12 OR 5.13,
REGARDLESS OF CAUSE OR ORIGIN, INCLUDING NEGLIGENCE OF SUCH PARTIES, ANY
MORTGAGEE, ANY SUPERIOR LESSOR AND EACH OF THEIR RESPECTIVE PARTNERS,
SHAREHOLDERS, MEMBERS, OFFICERS, DIRECTORS, EMPLOYEES, AGENTS (INCLUDING
BUILDING MANAGERS), AND AGREES THAT NO INSURER UNDER SUCH POLICIES SHALL HOLD
ANY RIGHT OF SUBROGATION AGAINST SUCH OTHER PARTY. IT IS THE INTENTION OF BOTH
LANDLORD AND TENANT THAT THE WAIVER OF SUBROGATION CONTAINED IN THIS SECTION
5.15 APPLY TO ALL CLAIMS DESCRIBED HEREIN, INCLUDING, WITHOUT LIMITATION, ANY OF
THE SAME THAT ARE CAUSED, IN WHOLE OR IN PART, BY LANDLORD, TENANT OR THEIR
RESPECTIVE VISITORS, EMPLOYEES, CONTRACTORS, AGENTS OR INVITEES.

      SECTION 5.16 NAME OF BUILDING The Building shall continue to be named "The
Williams Tower" until such time as Landlord may decide, in its sole discretion,
to change the name of the Building. In the event Landlord decides to change the
name of the Building, (i) Landlord shall (A) give Tenant 90 days' prior written
notice of its intention to change the name of the Building (upon receipt of such
notice Tenant shall cease to use the name of the Building for any purpose other
than its mailing address), (B) pay any costs related to changing external
graphics on the Building to reflect the change in name, and (C) reimburse Tenant
for the costs (not to exceed $10,000) incurred by Tenant internally in
connection with the change in name, including updating Tenant's professional
stationary and employees business cards, and (ii) Tenant shall have the
exclusive use of a monument sign, to be constructed and installed at Tenant's
cost and expense, located in front of the Building and similar to the monument
signs of

                                       57
<PAGE>

other tenants in the Building, subject to Landlord's approval with respect to
architectural design, graphics, exact location and size.

      SECTION 5.17 SURVIVAL

      All of Tenant's covenants and obligations contained in this Lease shall
survive the expiration or earlier termination of this Lease. No provision of
this Lease providing for termination in certain events shall be construed as a
limitation or restriction of Landlord's rights and remedies at law or in equity
available upon a breach by Tenant of this Lease.

      SECTION 5.18 ENTIRE AGREEMENT

      This Lease and the Schedules and Exhibits attached hereto contain the
entire agreement of the parties. No other written or oral promises or
representations have been made, and none shall be binding. This Lease supersedes
and replaces any previous lease between the parties, including the 1981 Lease
and any renewals or extensions thereof (except to the extent of any provisions
of the 1981 Lease that expressly survive termination or expiration in accordance
with terms thereof). On or prior to the Commencement Date, Tenant shall
surrender possession to Landlord of that portion of the space demised to Tenant
under the 1981 Lease not included in the Leased Premises in the condition
required under the 1981 Lease. Landlord's agents do not and will not have
authority to (a) make exceptions, changes or amendments to this Lease or factual
representations not expressly contained in this Lease, (b) waive any right,
requirement, or provision of this Lease, or (c) release Tenant from all or part
of this Lease, unless such action is in writing.

      SECTION 5.19 TIME IS OF THE ESSENCE

      TIME IS OF THE ESSENCE WITH RESPECT TO ALL DATES, DEADLINES AND TIME
PERIODS SET FORTH IN THIS LEASE AND ALL PERFORMANCE DUE DATES, TIME SCHEDULES,
AND CONDITIONS PRECEDENT TO EXERCISING A RIGHT HEREUNDER SHALL BE STRICTLY
ADHERED TO WITHOUT DELAY EXCEPT WHERE OTHERWISE EXPRESSLY PROVIDED.

      SECTION 5.20 FORCE MAJEURE

      (a) If, by reason of Force Majeure, Landlord or Tenant shall be unable to
fulfill its obligations under this Lease (other than an obligation that may be
satisfied by or upon the payment of money), then such party shall not be deemed
in breach of such obligations and shall have no liability therefor (and the same
shall not be deemed a constructive eviction) and such party's obligations
hereunder shall in no way be affected, impaired or excused (except to the extent
prevented by such party's inability to fulfill its obligations hereunder).

      (b) "Force Majeure" means fire, casualty, any strike, lock-out or other
labor trouble, governmental preemption of priorities or other controls in
connection with a national or other public emergency or shortages of fuel,
supplies or labor resulting therefrom, or any other cause, whether similar or
dissimilar, beyond Landlord's reasonable control; or any failure or defect in

                                       58
<PAGE>

the supply, quantity or character of electricity or water furnished to the
Leased Premises, by reason of any requirement, act or omission of the utility or
others serving the Project with electric energy, steam, oil, gas or water, or
for any other reason whether similar or dissimilar, beyond Landlord's reasonable
control.

      (c) To the extent commercially feasible, Landlord shall use commercially
reasonable efforts to minimize the duration of any delay caused by Force
Majeure, except that such obligation shall not require Landlord to employ
contractors or labor at overtime or other premium pay rates or to incur any
other overtime costs or additional expenses (other than de minimis amounts).
This Section 5.20 shall not impair or adversely affect Tenant's rights under (i)
Section 3.05 or 410. (ii) Section 5.06 with respect to a Casualty Condition or
(ii) Section 5.01 with respect to a condemnation or conveyance in lieu thereof.

      SECTION 5.21 BROKERS

      Tenant hereby warrants and represents that it has not dealt with any other
brokers or intermediaries entitled to any compensation in connection with this
Lease or Tenant's occupancy of space in the Leased Premises other than the Named
Broker, which shall be paid a commission by Landlord pursuant to a separate
agreement between Landlord and such broker. Each party hereby agrees to hold the
other party, its partners and representatives harmless from any and all claims,
liabilities, costs and expenses (including reasonable attorneys' fees) arising
from any claim for any commission or other fees by any other broker or agent
acting or purporting to have acted on behalf of such party other than the Named
Broker.

      SECTION 5.22 NO WARRANTIES

      THE OBLIGATION OF TENANT TO PAY RENT AND PERFORM TENANT'S OTHER COVENANTS
AND DUTIES UNDER THIS LEASE ARE INDEPENDENT, UNCONDITIONAL OBLIGATIONS THAT ARE
TO BE PERFORMED AT THE TIMES PROVIDED FOR IN THIS LEASE. TENANT WAIVES AND
RELINQUISHES ALL RIGHTS TO CLAIM ANY NATURE OF LIEN AGAINST RENT. TENANT WAIVES
AND RELINQUISHES ANY RIGHT TO ASSERT THAT LANDLORD IS BOUND TO PERFORM (OR IS
LIABLE FOR NONPERFORMANCE OF) ANY IMPLIED COVENANTS OR DUTIES OF LANDLORD THAT
ARE NOT STATED IN THIS LEASE. TENANT WAIVES ANY IMPLIED WARRANTY BY LANDLORD
THAT THE LEASED PREMISES ARE SUITABLE FOR THEIR INTENDED COMMERCIAL PURPOSE, AND
ACKNOWLEDGES THAT TENANT'S OBLIGATIONS ARE INDEPENDENT OF ANY SUCH IMPLIED
WARRANTY AND OF ALL OTHER COVENANTS AND OBLIGATIONS OF LANDLORD. TENANT AGREES
THAT LANDLORD WILL INCUR NO LIABILITY TO TENANT DUE TO ANY APPARENT OR LATENT
DEFECT IN THE LEASED PREMISES. LANDLORD MAKES NO EXPRESS OR IMPLIED WARRANTY
REGARDING THE CONDITION OF THE LEASED PREMISES. NEITHER LANDLORD NOR TENANT
SHALL BE LIABLE UNDER THIS LEASE FOR ANY PUNITIVE, CONSEQUENTIAL, OR SPECIAL
DAMAGES.

                                       59
<PAGE>

      SECTION 5.23 NOTICES

      All notices, demands, consents and approvals which may or are required to
be given by either party to the other hereunder shall be in writing and shall be
deemed to have been delivered (i) on the date personally delivered, (ii) on the
Business Day immediately after the date delivered to a nationally recognized
overnight courier for overnight delivery or (iii) on the third Business Day
immediately after the date deposited in the United States mail, certified or
registered, postage prepaid, in each case, addressed to the party to be notified
if to Landlord to the addresses set forth in Schedule 1, or if to Tenant to the
addresses set forth in Schedule 1, or to such other place as the party to be
notified may from time to time designate upon at least 15 days prior notice to
the notifying party.

      SECTION 5.24 SEVERABILITY

      If any term or provision of this Lease, or the application thereof to any
Person or circumstance shall to any extent be invalid or unenforceable, the
remainder of this Lease, or the application of such provision to Persons or
circumstances other than those as to which it is invalid or unenforceable, shall
not be affected thereby. Each provision of this Lease shall be valid and shall
be enforceable to the extent permitted by law.

      SECTION 5.25 AUTHORITY

      (a) Tenant represents and warrants to Landlord that (i) Tenant is a
corporation duly formed, validly existing and in good standing under the laws of
the State of Delaware, (ii) Tenant is authorized to do business in the State of
Texas, (iii) that the person executing this Lease on behalf of Tenant was
authorized to do so, (iv) all consents or approvals required from third parties
(including its Board of Directors) for the execution, delivery and performance
of this Lease have been obtained and (v) upon request of Landlord, Tenant will
deliver to Landlord evidence of such person's authority to execute and deliver
this Lease on behalf of Tenant.

      (b) Landlord represents and warrants to Tenant that (i) Landlord is a
limited partnership duly formed, validly existing and in good standing under the
laws of the State of Texas, (ii) that the person executing this Lease on behalf
of Landlord was authorized to do so, (iii) all consents or approvals required
from third parties for the execution, delivery and performance of this Lease
have been obtained and (iv) upon request of Tenant, Landlord will deliver to
Tenant evidence of such person's authority to execute and deliver this Lease on
behalf of Landlord.

      SECTION 5.26 MUTUAL WAIVERS OF JURY TRIAL AND CERTAIN DAMAGES

      TENANT AND LANDLORD EACH HEREBY EXPRESSLY, IRREVOCABLY, FULLY AND FOREVER
RELEASES, WAIVES AND RELINQUISHES ANY AND ALL RIGHT TO TRIAL BY JURY AND ALL
RIGHT TO RECEIVE PUNITIVE, EXEMPLARY AND CONSEQUENTIAL DAMAGES FROM THE OTHER
(OR ANY PAST, PRESENT OR FUTURE BOARD MEMBER, TRUSTEE, DIRECTOR, OFFICER,
EMPLOYEE, AGENT,

                                       60

<PAGE>

REPRESENTATIVE, OR ADVISOR OF THE OTHER) IN ANY CLAIM, DEMAND, ACTION, SUIT,
PROCEEDING OR CAUSE OF ACTION IN WHICH THE TENANT AND LANDLORD ARE PARTIES,
WHICH IN ANY WAY (DIRECTLY OR INDIRECTLY) ARISES OUT OF, RESULTS FROM OR RELATES
TO ANY OF THE FOLLOWING, IN EACH CASE WHETHER NOW EXISTING OR HEREAFTER ARISING
AND WHETHER BASED ON CONTRACT OR TORT OR ANY OTHER LEGAL BASIS: (I) THIS LEASE;
(II) ANY PAST, PRESENT OR FUTURE ACT, OMISSION, CONDUCT OR ACTIVITY WITH RESPECT
TO THIS LEASE; (III) ANY TRANSACTION, EVENT OR OCCURRENCE CONTEMPLATED BY THIS
LEASE; (IV) THE PERFORMANCE OF ANY OBLIGATION OR THE EXERCISE OF ANY RIGHT UNDER
THIS LEASE; OR (V) THE ENFORCEMENT OF THIS LEASE. TENANT AND LANDLORD EACH
AGREES THAT THIS LEASE CONSTITUTES WRITTEN CONSENT THAT TRIAL BY JURY SHALL BE
WAIVED IN ANY SUCH CLAIM, DEMAND, ACTION, SUIT, PROCEEDING OR OTHER CAUSE OF
ACTION AND AGREES THAT TENANT AND LANDLORD EACH SHALL HAVE THE RIGHT AT ANY TIME
TO FILE THIS LEASE WITH THE CLERK OR JUDGE OF ANY COURT IN WHICH ANY SUCH CLAIM,
DEMAND, ACTION, SUIT, PROCEEDING OR OTHER CAUSE OF ACTION MAY BE PENDING AS
STATUTORY WRITTEN CONSENT TO WAIVER OF TRIAL BY JURY IN ACCORDANCE WITH RULES
AND PROCEDURES OF ANY COURT.

      SECTION 5.27 BINDING EFFECT

      This Lease shall be binding upon and inure to the benefit of the
successors and assigns of Landlord, and shall be binding upon and inure to the
benefit of Tenant, its successors and permitted assigns. The pronouns of any
gender shall include the other genders, and either the singular or the plural
shall include the other.

      SECTION 5.28 CUMULATIVE

         All rights and remedies of Landlord under this Lease shall be
 cumulative and none shall exclude any other rights or remedies allowed by law
 unless expressly stated herein to the contrary; and this Lease is a Texas
 contract, and all of the terms hereof shall be construed according to the laws
 of the State of Texas.

                                   ARTICLE 6
                                RENEWAL OPTIONS

         SECTION 6.01   RENEWAL OPTIONS; EXERCISE OF OPTIONS

      (a) Tenant shall have the option to renew this Lease for three (3)
successive renewal terms of five (5) years each (each a "Renewal Term" and
collectively the "Renewal Terms") with respect to any portion of the Leased
Premises that, on either the date of Tenant's Renewal Notice or the commencement
date of the applicable Renewal Term, (i) has not been subleased to any Person
(other than (any successor by merger, consolidation or purchaser of
substantially all of the assets of Transcontinental Gas Pipe Line Corporation,
in each case, as expressly permitted

                                       61
<PAGE>

hereunder, collectively, a "Transco Related Party") and (ii) does not constitute
any portion of a floor of the Leased Premises of which more than 50% of the Net
Rentable Area has been subleased to any Person (other than a Transco Related
Party). The Renewal Terms shall be for the following terms (unless this Lease or
either of the Renewal Terms shall sooner terminate pursuant to any of the terms
of this Lease or otherwise):

                  (i) the first renewal term (the "First Renewal Term") shall
            commence at 12:00 A.M. C.S.T. on April 1,2014 and end at 11:59 P.M.
            C.S.T. on March 31, 2019;

                  (ii) the second renewal term (the "Second Renewal Term") shall
            commence at 12:00 A.M. C.S.T. on April 1, 2019 and end at 11:59 P.M.
            C.S.T. on March 31, 2024; and

                  (iii) the third renewal term (the "Third Renewal Term") shall
            commence at 12:00 A.M. C.S.T. on April 1, 2024 and end at 11:59 P.M.
            C.S.T. on March 31,2029.

      (b) In the event Tenant desires to exercise any renewal right set forth in
Section 6.01 (a), Tenant shall exercise such right by written notice (the
"Renewal Notice") of such election delivered to Landlord as follows (TIME SHALL
BE OF THE ESSENCE WITH RESPECT TO THE FOLLOWING DATES):

                  (i) not earlier than March 31, 2012 and not later than
            September 30, 2012 with respect to the First Renewal Term;

                  (ii) not earlier than March 31, 2017 and not later than
            September 30, 2017, with respect to the Second Renewal Term; and

                  (iii) not earlier than March 31, 2022 and not later than
            September 30, 2022, with respect to the Third Renewal Term.

      (c) Tenant's failure to timely exercise its renewal right as provided in
this Section 6.01 shall render any subsequent attempted exercise void and of no
effect, any principles of law to the contrary notwithstanding. Tenant shall not
be permitted to renew this Lease for the Second Renewal Term unless this Lease
has been renewed for the First Renewal Term and Tenant shall not be permitted to
renew this Lease for the Third Renewal Term unless this Lease has been renewed
for the Second Renewal Term, in each case, in accordance with the terms of this
Lease. In addition, Tenant shall have no right to exercise its option to renew
this Lease, and any attempted exercise shall be void and of no effect, if:

                  (i) Tenant has delivered the Termination Notice;

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<PAGE>

                  (ii) Tenant shall be in default hereunder beyond the
            expiration of any applicable notice and grace period on either the
            date of Tenant's delivery of the Renewal Notice or the commencement
            date of the applicable Renewal Term; or

                  (iii) this Lease shall not be in full force and effect on
            either the date of Tenant's delivery of the Renewal Notice or the
            commencement date of the applicable Renewal Term.

      SECTION 6.02 TERMS OF RENEWAL TERM

      (a) Each Renewal Term shall be upon all of the terms and conditions of
this Lease, except that:

                  (i) the Base Rental payable during each Renewal Term shall be
            as follows:

                  (1)   for the First Renewal Term, an annual rate per Net
                        Rentable Area of the Leased Premises equal to 95% of the
                        Market Rental as of the first day of the First Renewal
                        Term (which such amount shall include escalations during
                        the First Renewal Term);

                  (2)   for the Second Renewal Term, an annual rate per Net
                        Rentable Area of the Leased Premises equal to the Market
                        Rental as of the first day of the Second Renewal Term
                        (which such amount shall include escalations during the
                        Second Renewal Term); and

                  (3)   for the Third Renewal Term, an annual rate per Net
                        Rentable Area of the Leased Premises equal to the Market
                        Rental as of the first day of the Third Renewal Term
                        (which such amount shall include escalations during the
                        Third Renewal Term).

                  (ii) the Leased Premises shall be delivered in its then
            existing condition (on an "AS IS" basis) at the time the applicable
            Renewal Term commences; and

                  (iii) there shall be no further option to renew beyond the
            expiration of the Third Renewal Term.

            (b) (i) The Market Rental shall be determined by Landlord by notice
            (the "Market Rental Notice") delivered to Tenant not later than 60
            days after Landlord's receipt of Tenant's Renewal Notice or, if
            Tenant shall dispute Landlord's determination by notice ("Tenant's
            Dispute Notice"') delivered to Landlord not later than 30 days after
            Tenant's receipt of the Market Rental Notice, then such value shall
            be determined in by arbitration as provided in Section 6.03.
            Landlord's determination of the Market Rental as set forth in the
            Market Rental Notice shall be deemed conclusive and binding upon
            Tenant if Tenant fails to

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<PAGE>

            deliver Tenant's Dispute Notice within such 30-day period, unless
            within such 30-day period, Tenant delivers notice to Landlord
            revoking Tenant's Renewal Notice, in which case, the Tenant Renewal
            Notice shall be deemed revoked and Tenant shall have no further
            renewal rights under this Article.

                  (ii) If arbitration concerning the Market Rental shall not be
            concluded before the commencement of the applicable Renewal Term,
            then Tenant shall pay Base Rental to Landlord from and after the
            commencement of the applicable Renewal Term as specified in the
            Market Rental Notice. If the Market Rental as determined by
            arbitration is greater than or less than that specified in the
            Market Rental Notice, then an adjustment required to correct the
            amount previously paid on account of Base Rental shall be made by
            the appropriate party within 30 days after the arbitration
            determination, plus interest thereon at an annual rate equal to the
            lesser of (1) the Base Rate and (2) the highest rate permitted at
            law, calculated from the date when the same was due or paid, as the
            case may be, to the date when the same is paid or refunded, as the
            case may be.

      (c) "Market Rental" means the annual fair market rental value per Net
Rentable Area (determined on a "net" lease basis) of the Leased Premises at the
commencement of the applicable Renewal Term for a term equal to the applicable
Renewal Term, based on comparable space in Comparable Buildings for similar
sized space in recent transactions, taking into account all relevant factors,
including the following:

                  (i) the location, quality and age of the Building;

                  (ii) size and location of the Leased Premises;

                  (iii) the Leased Premises shall be considered given the extent
            of leasehold improvements existing at such time based upon the
            "AS-IS" condition existing as of the commencement of the applicable
            Renewal Term;

                  (iv) rental abatements, lease takeover/assumption, moving
            expenses, tenant finish allowances and other concessions;

                  (v) term of the applicable Renewal Term;

                  (vi) all of Landlord's services provided for in this Lease;

                  (vii) the parties' rights and obligations under this Lease
            (including the fact that Base Rental payable under this Lease is
            paid on a net basis);

                  (viii) creditworthiness of Tenant (Tenant shall deliver to
            Landlord all relevant financial statements reasonably requested by
            Landlord necessary for Landlord to determine the creditworthiness of
            Tenant in connection with the foregoing);

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<PAGE>

                  (ix) the period during which such rent is to become effective;
            and

                  (x) the assumption that Landlord has an obligation to pay a
            market leasing brokerage commission in connection with Tenant's
            renewal of this Lease for the applicable Renewal Term (regardless of
            whether Landlord has any obligation to actually pay any such
            commission).

      For the purposes of this Section 6.02(c) only, the term "similar sized
      space" shall mean space constituting at least 60,000 net rentable square
      feet.

      SECTION 6.03 ARBITRATION

      If Tenant delivers Tenant's Dispute Notice within the 30-day period set
forth in Section 6.02(b)(i), then in such case, the Market Rental shall be
determined by arbitration before a single arbitrator in accordance with the
following:

      (a) For the 20-day period immediately after delivery of Tenant's Dispute
Notice, Landlord and Tenant shall negotiate, in good faith, to select a mutually
agreeable arbitrator. If Landlord and Tenant fail to agree on an arbitrator
within such 20-day period, Landlord shall, on behalf of the parties, promptly
request the AAA appoint an arbitrator for the purposes set forth herein. The AAA
shall be instructed to appoint, as arbitrator, an individual with the following
qualifications: licensed commercial real estate broker; ten (10) years' current
and active experience in the business of leasing commercial real estate in
Comparable Buildings; generally recognized competence in the representation of
landlords or tenants in commercial leasing transactions in Comparable Buildings,
Texas; and such individual has never been a direct or indirect employee,
Affiliate or agent of either Landlord or Tenant. The AAA shall be instructed to
appoint such arbitrator (i) in accordance with the AAA's standard procedures
governing the selection of an arbitrator on behalf of arbitrating parties and
(ii) within 20 days after Landlord's request therefor. The arbitrator selected
by the AAA shall be binding upon Landlord and Tenant.

      (b) Landlord and Tenant shall each submit to the arbitrator, in writing,
each party's good faith determination of the Market Rental of the Leased
Premises.

      (c) The arbitrator shall select one of the good faith determinations
submitted by the parties pursuant to subsection (b) as the one which, in the
arbitrator's reasonable and professional judgment, is the most accurate
determination of the Market Rental of the Leased Premises, and the arbitrator's
choice shall be final and binding upon the parties.

      (d) The arbitrator shall render its decision within 45 days after the date
of appointment.

      (e) The decision by the arbitrator shall be final, binding and conclusive
and shall be non-appealable and enforceable in any court having jurisdiction.
All hearings and proceedings held by the arbitrator shall take place in Houston,
Texas.

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<PAGE>

      (f) The dispute resolution procedures set forth in this Section 6.03 shall
be governed by the Commercial Rules of the American Arbitration Association,
subject to the Texas General Arbitration Act to the extent such act is
applicable to such procedures.

      (g) The fees and expenses of the arbitrator shall be paid by Tenant in the
event the arbitrator shall select Landlord's good faith determination as the
most accurate determination of the Market Rental of the Leased Premises. The
fees and expenses of the arbitrator shall be paid by Landlord in the event the
arbitrator shall select Tenant's good faith determination as the most accurate
determination of the Market Rental of the Leased Premises. Landlord and Tenant
shall each pay the fees and expenses of their respective consultants and
attorneys and all other expenses incurred by such party in connection with the
arbitration.

                                    ARTICLE 7
                              RIGHT OF FIRST OFFER

      SECTION 7.01 RIGHT OF FIRST OFFER

      For so long as Transcontinental Gas Pipe Line Corporation or a Transco
Related Party shall be the tenant under this Lease, Tenant shall have a right of
first offer to lease space in the Building on Level 8, Level 18 and Level 19
(each a "ROFO Space") in accordance with the terms of this Article. Tenant's
rights hereunder in respect of each ROFO Space shall be subject and subordinate
to the pre-existing rights of all existing tenants at the Building (i.e. tenants
at the Building as of the date of this Lease).

      SECTION 7.02 PROCEDURE

            (a) In the event that Landlord desires to lease any of the ROFO
      Space, Landlord shall deliver a notice (the "ROFO Notice") to Tenant
      setting forth the terms and conditions upon which Landlord is willing to
      lease the applicable ROFO Space to Tenant, which such terms and conditions
      shall reflect a base rental equal to the greater of (i) the applicable
      Base Rental payable hereunder in respect of the Leased Premises during the
      same period for which the ROFO Space is proposed to be leased to Tenant
      and (ii) an annual rate per Net Rentable Area of the applicable ROFO Space
      equal to the Market Rental as of the first day of the commencement of the
      term for the leasing of the applicable ROFO Space (which such amount shall
      include escalations during the applicable term). Landlord's ROFO Notice
      shall include Landlord's determination ("Landlord's Determination") of the
      Market Rental for the applicable ROFO Space.

            (b) For the 30-day period (the "ROFO Period") immediately following
      Landlord's delivery of the ROFO Notice, Tenant shall have the exclusive
      right to negotiate with Landlord for the leasing of the applicable ROFO
      Space. Landlord and Tenant shall negotiate in good faith during the ROFO
      Period for the leasing of the applicable ROFO Space. Subject to Tenant's
      right to dispute Landlord's Determination in accordance with Section 7.03,
      if prior to the expiration of the ROFO Period, Landlord and Tenant have
      reached a definitive agreement on all of the terms and conditions upon

                                       66
<PAGE>

      which the parties are willing to enter into a lease for the applicable
      ROFO Space, Landlord and Tenant shall, within the ROFO Period, enter into
      a lease (or an amendment to this Lease) setting forth such terms (subject
      to final determination of the Market Rental pursuant to Section 7.03, if
      applicable). The parties acknowledge, that it is their intention that the
      terms and conditions of the leasing of the ROFO Space be on substantially
      the same terms and conditions of this Lease, except with respect to (i)
      the base rental, which shall be determined as set forth in Section
      7.02(a), (ii) those terms and conditions which, by their nature, shall not
      apply and (iii) to the extent as may be otherwise agreed between the
      parties within the ROFO Period.

            (c) If Landlord and Tenant are unable to reach a definitive
      agreement prior to the expiration of the ROFO Period upon which the
      parties are willing to enter into a lease for the applicable ROFO Space,
      then upon the expiration of the ROFO Period (i) Landlord shall be free to
      lease the applicable ROFO Space to any Person upon any terms that Landlord
      may desire. It is the intent of Landlord and Tenant that Tenant have a
      continuing right of first opportunity to lease the ROFO Space, subject to
      the terms and conditions set forth in this Section 7.02.

      SECTION 7.03 DETERMINATION OF MARKET RENTAL

            (a) If prior to the expiration of the ROFO Period Landlord and
      Tenant reach a definitive agreement on all of the terms and conditions
      upon which the parties are willing to enter into a lease for the
      applicable ROFO Space except that Tenant, in good faith, disputes
      Landlord's Determination, then Tenant shall notify Landlord of such
      dispute prior to the expiration of the ROFO Period. In the event Tenant
      fails to dispute Landlord's Determination prior to the expiration of the
      ROFO Period, Landlord's Determination shall be deemed conclusive and
      binding upon Tenant.

            (b) In the event Tenant timely disputes Landlord's Determination in
      accordance with subsection (a), the Market Rental shall be determined in
      accordance with the arbitration procedure and terms and provisions set
      forth in Section 6.03.

            (c) If arbitration concerning the Market Rental shall not be
      concluded before the commencement of the term for the applicable ROFO
      Space, then Tenant shall pay Base Rental to Landlord from and after the
      commencement of the applicable term with respect to the leasing of the
      applicable ROFO Space to Tenant as specified in Landlord's Determination.
      If the Market Rental as determined by arbitration is greater than or less
      than that specified in Landlord's Determination, then an adjustment
      required to correct the amount previously paid on account of Base Rental
      shall be made by the appropriate party within 30 days after the
      arbitration determination, plus interest thereon at an annual rate the
      lesser of (1) the Base Rate and (2) the highest rate permitted at law,
      calculated from the date when the same was due or paid, as the case may
      be, to the date when the same is paid or refunded, as the case may be.

                                       67
<PAGE>

      SECTION 7.04 ADDITIONAL CONDITIONS

      Tenant's rights under this Article with respect to any particular ROFO
Space shall be null and void, if at either the time of Landlord's delivery of
the ROFO Notice with respect to such ROFO Space or upon the commencement of the
term for such ROFO Space, either (i) this Lease shall not be in full force and
effect or (ii) there shall exist a Material Event of Default.

      SECTION 7.05 TIME OF THE ESSENCE

      TIME SHALL DE OF THE ESSENCE WITH RESPECT TO ALL TIME PERIODS SET FORTH IN
THIS ARTICLE.

                                   ARTICLE 8
                             RIGHT OF FIRST REFUSAL

      SECTION 8.01 RIGHT OF FIRST REFUSAL

      In addition to Tenant's rights under Article 7 and For so long as
Transcontinental Gas Pipe Line Corporation or a Transco Related Party shall be
the tenant under this Lease, Tenant shall have an on-going right of first
refusal (the "ROFR") to lease available space in the Building on Level 8, 18 and
Level 19 at such time (collectively, the "ROFR Space") in accordance with the
terms of this Article. Tenant's ROFR hereunder shall be subject and subordinate
to the currently pre-existing rights of all currently existing tenants at the
Building (i.e. tenants at the Building as of the date of this Lease).

      SECTION 8.02 CONDITIONS

      Tenant's ROFR rights under this Article with respect to any particular
ROFR Space shall be null and void, if at either the time of Tenant's acceptance
of the ROFR Offer with respect to such ROFR Space or upon the commencement of
the term for such ROFR Space, either (i) this Lease shall not be in full force
and effect or (ii) there shall exist a Material Event of Default.

      SECTION 8.03 APPLICABLE TERMS FOR RIGHT OF FIRST REFUSAL

      If at any time during the Term Landlord shall receive a bona fide offer (a
"ROFR Offer") from a third-party to lease any of the ROFR Space, which offer
Landlord shall desire to accept, Landlord shall promptly deliver to Tenant a
true, correct and complete copy of such offer, and Tenant may, within 10
Business Days thereafter, irrevocably elect to lease such ROFR Space on the same
terms (without any variation whatsoever) as those set forth in such offer. If
Tenant shall not accept such offer within such 10-Business Day period, Landlord
shall be permitted to lease the applicable ROFR Space to any Person upon terms
and conditions no more favorable to the tenant than those offered to Tenant in
the ROFR Offer (or in a subsequent ROFR Offer with respect to such ROFR Space).
If Tenant shall exercise the ROFR to lease the applicable ROFR Space in
accordance with the foregoing, Tenant shall, within 30 days, enter into an
amendment to this Lease effectuating the leasing of the ROFR Space on the agreed
terms. The failure of Tenant to enter into an amendment to this Lease in
accordance with the foregoing shall constitute an

                                       68

<PAGE>

irrevocable waiver by Tenant of the ROFR in respect of the applicable ROFR
Offer. If (a) Landlord does not lease the applicable ROFR Space on terms and
conditions no more favorable to the tenant that those offered to Tenant in the
ROFR Offer within 180 days after the expiration of the ROFR Period or (b)
Landlord does lease the ROFR Space and such space subsequently becomes available
for lease, then, in each case, Tenant's right of first refusal under this
Article shall again be applicable to such space on the terms and conditions set
forth in this Section 8.03. It is the intent of the parties that Tenant has a
continuing right of first refusal to lease the ROFR Space during the Term,
subject to the terms and conditions set forth in this Section 8.03.

      SECTION 8.04 TIME OF THE ESSENCE

      TIME SHALL BE OF THE ESSENCE WITH RESPECT TO ALL TIME PERIODS SET FORTH IN
THIS ARTICLE.

                                    ARTICLE 9
                                CLUB MEMBERSHIPS

      Landlord shall arrange for ten (10) memberships to the University Club
located within the Galleria Complex to be issued to Tenant for use by Tenant's
designated employees. Landlord shall pay for all initiation fees associated with
such memberships and Tenant shall pay for (i) all other costs and dues
associated with such memberships and (ii) all charges for goods and services
provided to the users of such memberships.

      THIS LEASE IS NOT TO BE CONSTRUED AS BINDING UPON LANDLORD OR TENANT UNTIL
THE SAME IS EXECUTED BY LANDLORD'S AND TENANT'S AUTHORIZED REPRESENTATIVES IN
THE SPACE PROVIDED BELOW.

                        (SIGNATURES APPEAR ON NEXT PAGE)

                                       69

<PAGE>

      IN TESTIMONY WHEREOF, the parties hereto have executed this Lease as of
the date written above.

LANDLORD                                     TENANT

TRANSCO TOWER LIMITED, a Texas               TRANS CONTINENTAL GAS PIPE LINE
limited partnership                          CORPORATION, a Delaware corporation

BY:   McCue Street Investors LLC, a
      Delaware limited liability company,    By /s/ J. D. Whuenant
      its  general partner                      -----------------------------
                                             Name: J. D. Whuenant
                                             Title: Senior Vice President

      By ________________________________
      Name:
      Title:

      By ________________________________
      Name:
      Title:

                                       70

<PAGE>

                                   SCHEDULE 1

                                   DEFINITIONS

      The following terms shall have the meanings set forth opposite such term
for the purposes of this Lease:

"1981 Lease"             has the meaning given in Section 1.05.

"AAA"                    has the meaning given in Section 2.05(d)(iii)(l).

"Actual Cost"            means Landlord's actual, verifiable out-of-pocket
                         costs, with no internal administrative fee or charge
                         added thereto.

"Actual Operating        has the meaning given in Section 2.05(a).
Expenses"

"Addresses for Notices"  (i)  If to Landlord:

                              Transco Tower Limited
                              2800 Post Oak Boulevard
                              Houston, Texas 77056
                              Attention: Property Manager

                              together with a copy sent in the manner
                              required by Section 5.23 to each of:

                              Transco Tower Limited
                              c/o Fosterlane Management Corporation
                              3715 Northside Parkway
                              400 Northcreek, Suite 700
                              Atlanta, Georgia 30327
                              Attention: Vice President

                              and

                              Shearman & Sterling LLP
                              599 Lexington Avenue
                              New York, New York 10022
                              Attention: Real Estate Notices/CMS 3724/202

                         (ii) If to Tenant:

                              TRANSCONTINENTAL GAS PIPE LINE CORPORATION
                              Williams Tower
                              2800 Post Oak Boulevard

                                       1
<PAGE>

                                   Suite 1200
                                   Houston Texas 77056
                                   Attention: Douglas Whisenant, President

                                   together with a copy sent in the manner
                                   required by Section 5.23 to:

                                   The Williams Companies, Inc.
                                   One Williams Center
                                   Suite 1800
                                   Tulsa, Oklahoma 74172
                                   Attention: George Shahadi

                                   and

                                   Fulbright & Jaworski LLP
                                   1301 McKinney, Suite 5100
                                   Houston, Texas 77010
                                   Attention: Kent Newsome, Esq.

"Additional Insured                has the meaning given in Section 5.23(f).
Parties"

"Additional Rent"                  means, collectively, any and all sums being
                                   due under this Lease other than Base Annual
                                   Rental including, without limitation,
                                   Tenant's Share of Forecast Operating
                                   Expenses and Tenant's Share of Actual
                                   Operating Expenses as set forth in
                                   Section 2.05.

"Affiliate"                        means, as to any Person, any other Person
                                   that, directly or indirectly through one or
                                   more intermediaries or otherwise, Controls
                                   (as hereinafter defined), is Controlled by,
                                   or is under common Control with, such
                                   Person, including, as to Landlord and Tenant,
                                   any Person controlling or controlled by or
                                   under common control with any general
                                   partner of Landlord or Tenant, as the
                                   case may be.

"Alterations"                      has the meaning given in Section 4.05(a).

"Audit Arbitration                 has the meaning given in Section 2.05(d)
Election Notice"                   (iii).

"Base Annual Rental" .             means the amounts set forth on Schedule 2.

"Base Rate"                        means the annual rate of interest publicly
                                   announced from time to time by JPMorgan
                                   Chase Bank, or its successor, in New York,
                                   New York

                                       2
<PAGE>

                                   as its "base rate" (or such other term as
                                   may be used by JPMorgan Chase Bank, from
                                   time to time, for the rate presently
                                   referred to as its "base rate").

"Base Rental"                      has the meaning given in Section 2.03(a).

"Base Rental Credit"               has the meaning given in Section 2.03(b).

"Base Rooftop Rental"              means the amounts set forth on Schedule 6.

"Building"                         means the building known, as of the date
                                   hereof, as Williams Tower situated on the
                                   Land (as hereinafter defined) and located
                                   at 2800 Post Oak Boulevard, Houston,
                                   Harris County, Texas 77056.

"Building Standard                 means a day other than (i) Sunday, (ii) New
 Days"                             Year's Day, Memorial Day, Independence Day,
                                   Labor Day, Thanksgiving Day,Christmas Day,
                                   (iii) a day on which commercial banks in
                                   Houston, Texas are authorized or required
                                   by law to close or (iv) holidays designated
                                   by any labor union governing employees
                                   involved in the management, operation
                                   or maintenance of the Project.

"Building Standard                 means the hours between 7:00 A.M. C.S.T. and
  Hours"                           6:00 P.M. C.S.T. on Mondays through Fridays
                                   and between 7:00 A.M. C.S.T. and 1:00 P.M.
                                   C.S.T. on Saturdays.

"Building Standard Rated            has the meaning given in Section 3.01(c).
 Electrical Design Load"

"Business Days"                    means days which are not (i) Saturdays,
                                   (ii) Sundays,(iii) a day on which commercial
                                   banks in Houston, Texas are authorized or
                                   required by law to close or (iv) holidays
                                   designated by any labor union governing
                                   employees involved in the management,
                                   operation or maintenance of the Project.

"Casualty Condition"               has the meaning given in Section 5.06(a).

"Code"                             has the meaning given in Section 5.03.

"Commencement Date"                means March 30, 2004.

"common areas"                     has the meaning given in Section 1.02.

"Comparable Buildings"             means office buildings substantially
                                   comparable to the Building (including with
                                   respect to age, condition and amenities)
                                   located in the Galleria/West Loop area,
                                   the Greenway Plaza area or the Southwest
                                   Freeway corridor of Houston, Texas.

                                       3
<PAGE>

"Contraction Date"                 has the meaning given in Section 1.03(a).

"Contraction Notice"               has the meaning given in Section 1.03(a).

"Contraction Payment"              has the meaning given in Section 1.03(b).

"Contracted Portion of the Leased  has the meaning given in Section 1.03(a).
Premises"

"Control"                          means the possession, direct or indirect,
                                   of the power to direct or cause the
                                   direction of the management of such
                                   controlled Person; the ownership, directly
                                   or indirectly, of at least 51% of the voting
                                   interest of such controlled Person; or the
                                   possession of the right to vote in the
                                   ordinary direction of its affairs of at
                                   least 51% of the voting interest in such
                                   controlled Person.

"Decorative Alterations"           has the meaning given in Section 4.05(e).

"Dispute Notice"                   has the meaning given in Section 2.05(d)
                                   (iii).

"Essential Services"               has the meaning given in Section 3.02(a).

"extra areas"                      has the meaning given in Section 1.02.

"First Renewal Term"               has the meaning given in Section 6.01(a)(i).

"Force Majeure"                    has the meaning given in Section 5.20(b).

"Garage"                           means the parking garage and parking
                                   facilities situated on the Land (together
                                   with any additional parking garage or
                                   parking facilities constructed on the land
                                   situated within the radius depicted on
                                   Exhibit C for use in connection with the
                                   Building).

"Garage Spaces"                    has the meaning given in Section 4.15(b).

"General Contractor"               has the meaning given in Schedule 4.

"Governmental Authority            means the United States of America, the City
(Authorities)"                     of Houston, the County of Harris or the State
                                   of Texas, or any political subdivision,
                                   agency, department, commission, board, bureau
                                   or instrumentality of any of the foregoing,
                                   or any landmarks preservation agency(or other
                                   entity designated or accepted for such
                                   purpose by any Governmental Authority or
                                   landmarks preservation agency), now existing
                                   or hereafter created, having jurisdiction
                                   over the Project or any portion thereof or
                                   the curbs, sidewalks, and areas adjacent
                                   thereto.

                                       4

<PAGE>

"Hazardous Substance"              has the meaning given in Section 4.07(b).

"Indemnitees"                      has the meaning given in Section 5.14(b).

"Initial Improvements"             has the meaning given in Section 4.12.

"Land"                             means the land particularly described
                                   by metes and bounds on Exhibit 3 attached
                                   hereto and made a part hereof, together with
                                   all additional land acquired or leased by
                                   Landlord for use in connection with the
                                   Project.

"Landlord"                         has the meaning given in the Preamble.

"Landlord's ADA Initial Work"      has the meaning given in Section 4.07(d).

"Landlord's                        has the meaning given in Section 4.04(b)
Assignment/Subletting
Response"             .

"Landlord's                        has the meaning given in Section 7.02(a).
Determination"

"Landlord's Operating              has the meaning given in Section 2.05(d)(ii).
Expense Statement"

"Landlord Party" and               have the meanings given in Section 4.07(b).
"Landlord Parties"

"Lease"                            has the meaning given in the Preamble.

"Leased Premises"                  means approximately 217,595 square feet of
                                   Net Rentable Area (as defined in Section
                                   1.02), constituting the following space in
                                   the Building (which such space is shown on
                                   the floor plans attached as Exhibit A):

                                        (a)  approximately 1,448 square feet
                                             of Net Rentable Area on Level B2;

                                        (b)  approximately 4,817 square feet
                                             of Net Rentable Area on Level B1;

                                        (c)  approximately 1,107 square feet
                                             of Net Rentable Area on Level 2;

                                        (d)  approximately 12,081 square feet
                                             of Net Rentable Area on

                                       5
<PAGE>
                                      Level 3;

                          (e) approximately 21,954 square feet of Net Rentable
                              Area on Level 9;

                          (f) approximately 21,968 square feet of Net Rentable
                              Area on Level 10;

                          (g) approximately 21,968 square feet of Net Rentable
                              Area on Level 11;

                          (h) approximately 21,968 square feet of Net Rentable
                              Area on Level 12;

                          (i) approximately 21,968 square feet of Net Rentable
                              Area on Level 13;

                          (j) approximately 21,968 square feet of Net Rentable
                              Area on Level 14;

                          (k) approximately 21,974 square feet of Net Rentable
                              Area on Level 15;

                          (l) approximately 21,985 square feet of Net Rentable
                              Area on Level 16;

                          (m) approximately 21,985 square feet of Net Rentable
                              Area on Level 17; and

                          (n) approximately 404 square feet of Net Rentable Area
                              on Level 65.

 "Legal Requirements"   has the meaning set forth in Section 4.07(a).

 "Losses"               has the meaning given in Section 5.14(c).

 "Market Rental"        has the meaning given in Section 6.02(c).

 "Material Event of     has the meaning given in Section 2.03(b)(ii).
 Default"

 "Market Rental Notice" has the meaning given in Section 6.02(b)(i).

 "Minimum Number of     means right to park up to 3 vehicles per 1,000
 Parking Spaces"        square feet of the Net Rentable Area of the Leased
                        Premises (which shall initially mean 653 vehicles,
                        i.e., 217,595 square feet divided by 1,000
                        multiplied by 3).

                                       6

<PAGE>

"Mortgagee"                   has the meaning given in Section 4.10(a).

"Named Broker"                means, collectively, Hines Interests Limited
                              Partnership and Staubach-Houston, Ltd.

 "Net Rentable Area (as       means approximately 217,595 square feet. Landlord
defined in Section 1.02)      and Tenant acknowledge that the Net Rentable Area
 of the Leased Premises"      of the Leased Premises includes an allocation of
                              common area on the floors on which the Leased
                              Premises are located and other areas not leased or
                              held for lease within the Building but which are
                              necessary or desirable for the proper utilization
                              of the Building or to provide customary services
                              to the Building.

"Net Rentable Area of the     means the floor area that is calculated from time
Building"                     to time in accordance with Section 1.02 (currently
                              the Net Rentable Area of the Building is
                              approximately 1,514,935).

"New Tenant"                  has the meaning given in Section 5.05.

"Nextira"                     has the meaning given in Section 4.05(j).

"Non-Disturbance              has the meaning given in Section 4.10(e).
Requirements"

"Other Communications         has the meaning given in Section 1.07(c)(xiv).
Equipment"

"Operating Expenses"          has the meaning given in Section 2.05(a).

"Person"                      means any individual, corporation, partnership,
                              limited liability company, limited liability
                              partnership, joint venture, estate, trust,
                              unincorporated association, business trust,
                              tenancy-in-common or other entity, or any
                              Governmental Authority.

"Profit"                      has the meaning given in Section 4.04(c).

"Project"                     means, collectively, the Land, Building, Garage
                              and all improvements, driveways, landscaping and
                              other amenities (including all skybridges located
                              thereon, but excluding the water wall and the
                              adjacent park area) situated on the Land (together
                              with any additional improvements constructed on
                              the Land for use in connection with any of the
                              foregoing).

"Related Entity"              has the meaning given in Section 4.04(i)(ii).

                                       7

<PAGE>

"Renewal Notice"              has the meaning given in Section 6.01(b).

"Renewal Term" and            have the meaning given in Section 6.01(a).
"Renewal Terms"

"Rent"                        means, collectively, all Base Annual Rental, Base
                              Rooftop Rental and Additional Rent payable
                              hereunder.

"Required Information"        has the meaning given in Section 4.04(b).

"Restoration Notice"          has the meaning given in Section 5.06(b).

"ROFR"                        has the meaning given in Section 8.01.

"ROFR Offer"                  has the meaning given in Section 8.03.

"ROFR Space"                  has the meaning given in Section 8.01.

"ROFO Notice"                 has the meaning given in Section 7.02(a).

"ROFO Period"                 has the meaning given in Section 7.02(b).

"ROFO Space"                  has the meaning given in Section 7.01.

"Roof Space"                  that portion of the Building's roof shown
                              on the plan attached as Exhibit D.

"Rooftop Equipment Closet"    means that portion of the Leased Premises
                              constituting approximately 404 square feet of Net
                              Rentable Area on Level 65 (as such portion is
                              shown on the plan attached as Exhibit A).

"Rooftop Equipment"           has the meaning given in Section 1.07(a).

"Second Renewal Term"         has the meaning given in Section 6.01(a)(ii).

"service areas"               has the meaning given in Section 1.02.

"Superior Lessor"             has the meaning given in Section 4.10(a).

"Tenant"                      has the meaning given in the Preamble.

"Tenant Architect"            has the meaning given in Schedule 4.

"Tenant Delay"                has the meaning given in Schedule 4.

"Tenant Dispute Notice"       has the meaning given in Section 6.02(b)(i).

                                       8

<PAGE>

"Tenant Indemnity                  has the meaning given in Section 5.14(c).
Parties"

"Tenant Party" and                 have the meanings given in Section 4.07(b).
"Tenant Parties"

"Tenant's Audit"                   has the meaning given in Section 2.05(d)
                                   (iii).

"Tenant Working                    has the meaning given in Schedule 4.
Drawings"

"Tenant's Audit Report"            has the meaning given in Section 2.05(d)
                                   (iii).

"Tenant's Chillers"                has the meaning given in Section 4.05 (j).

"Tenant's Service                  has the meaning given in Section 3.02(b).
Interruption Termination
Notice"

"Tenant's Share"                   has the meaning given in Section 2.05(c).

"Tenant's Share of                 has the meaning given in Section 2.05(c).
Forecast Operating
Expenses"

"Tenant's Termination              has the meaning given in Section 1.06(a).
Notice"

"Term"                             means a period of ten (10) years and
                                   two (2) days beginning at 12:00 A.M. C.S.T.
                                   on the Commencement Date and ending at 11:59
                                   P.M. C.S.T. on March 31, 2014 subject to all
                                   renewal rights hereunder) unless this Lease
                                   is sooner terminated in accordance with the
                                   terms hereof.

"Termination Date"                 has the meaning given in Section 1.06(c).

"Termination Payment"              has the meaning given in Section 1.06(b).

"Third Party Riser Space"          has the meaning given in Section 1.08(b).

"Third Renewal Term"               has the meaning given in Section 6.01(a)
                                   (iii).

"Transco Related Party"            has the meaning given in Section 6.01 (a)
                                   (iv).

"Underlying Lease"                 has the meaning given in Section 4.10(a).

                                       9
<PAGE>

"Underlying Mortgage"              has the meaning given in Section 4.10(a).

"Untenantable"                     has the meaning given in Section 5.01(c).

"UPS"                              means Tenant's uninterruptible power supply
                                   system located in the Building's central
                                   plant.

"Wiring"                           has the meaning given in Section 1.07(c)
                                   (iii).

"Working Drawings                  has the meaning given in Schedule 4.
Review Date"

                                       10
<PAGE>

                                   SCHEDULE 2

                               BASE ANNUAL RENTAL

<TABLE>
<CAPTION>
                                                     BASE ANNUAL RENTAL PER
LEASE                   PERIOD                        NET RENTABLE AREA OF
YEAR             (BOTH DATES INCLUSIVE)               THE LEASED PREMISES
------     -------------------------------------     ----------------------
<S>        <C>                                       <C>
 l         March 30, 2004 through March 31, 2005        $12.00 PSF/NET
 2         April 1, 2005 through March 31, 2006         $12.00 PSF/NET
 3         April 1, 2006 through March 31, 2007         $13.00 PSF/NET     .
 4         April 1, 2007 through March 31, 2008         $13.00 PSF/NET
 5         April 1, 2008 through March 31, 2009         $14.00 PSF/NET
 6         April 1, 2009 through March 31, 2010         $14.00 PSF/NET
 7         April 1, 2010 through March 31, 2011         $15.00 PSF/NET
 8         April 1, 2011 through March 31, 2012         $15.00 PSF/NET
 9         April 1, 2012 through March 31, 2013         $16.00 PSF/NET
 10        April 1, 2013 through March 31, 2014         $16.00 PSF/NET
</TABLE>

                                       11
<PAGE>

                                   SCHEDULE 3

                               BASE RENTAL CREDIT

<TABLE>
<CAPTION>
                                                        ASE AMOUNT OF BASE RENTAL
                                                             CREDIT PER NET
                                                          RENTABLE AREA OF THE
LEASE       PERIOD FOR WHICH CREDIT SHALL BE APPLIED         LEASED PREMISES
YEAR                 (BOTH DATES INCLUSIVE)                    (PER ANNUM)
------      ----------------------------------------    -------------------------
<S>         <C>                                         <C>
 1            March 30, 2004 through March 31, 2005             S2.50 PSF
 2            April 1, 2005 through March 31, 2006              $2.50 PSF
 3            April 1, 2006 through March 31, 2007              $2.50 PSF
 4            April 1, 2007 through March 31, 2008              $2.50 PSF
 5            April 1, 2008 through March 31, 2009              $2.50 PSF
 6            April 1, 2009 through March 31, 2010              $1.50 PSF
 7            April 1, 2010 through March 31, 2011              $1.50 PSF
 8            April 1, 2011 through March 31, 2012              $1.50 PSF
 9            April 1, 2012 through March 31, 2013              $1.50 PSF
10            April 1, 2013 through March 31, 2014              $1.50 PSF
</TABLE>

                                       12
<PAGE>

                                   SCHEDULE 4

                          TENANT'S INITIAL IMPROVEMENTS

                      PART I - PRE-CONSTRUCTION OBLIGATIONS

      1. Tenant shall retain and coordinate the services of a licensed and
reputable architectural firm (the "Tenant Architect") to prepare the documents
necessary for the construction of the Initial Improvements. Tenant's selection
of such architectural firm shall be subject to Landlord's prior approval. As of
the date hereof, Landlord agrees that the architectural firm of Hellmuth, Obata
+ Kassabaum, L.P. is hereby approved in connection with the performance of
Tenant's Initial Improvements. Tenant shall retain the services of the Building
engineers selected by Tenant and acceptable to Landlord to engineer the aspects
of the Initial Improvements relating to the structural, mechanical, electrical,
plumbing and fire protection systems, recognizing that the integrity of the
Building's systems shall be maintained through the use of the Building engineers
to design all systems. As of the date hereof, Landlord agrees that the
engineering firm of I.A. Narnan Associates, Inc. is hereby approved in
connection with the performance of Tenant's Initial Improvements.

      2. Tenant shall deliver to Landlord for Landlord's reasonable review
complete drawings and specifications prepared by the Tenant Architect and the
Building engineers showing all details for the layout and design of the Initial
Improvements (the "Tenant Working Drawings"). The Tenant Working Drawings shall
reflect Tenant's complete construction requirements, including, without
limitation, the information set forth in Part II attached hereto.

      3. Landlord shall review the Tenant Working Drawings and shall notify
Tenant of any revisions or additions required by Landlord within five (5)
Business Days after delivery to Landlord of the Tenant Working Drawings (the
fifth (5th) Business Day after the date that the Tenant Working Drawings are
delivered to Landlord being referred to herein as the "Working Drawings Review
Date"). If Landlord has not notified Tenant of any revisions or additions
required by it as aforesaid within such five (5) Business Day period, and
provided that such request expressly includes the following text in BOLD CAPITAL
LETTERING "LANDLORD'S APPROVAL OF THE ATTACHED TENANT WORKING DRAWINGS SHALL BE
DEEMED APPROVED IF LANDLORD DOES NOT RESPOND TO THIS REQUEST WITHIN 5 BUSINESS
DAYS HEREOF", then the Tenant Working Drawings shall be deemed approved as
submitted to Landlord.

      4. Tenant shall cause the Tenant Working Drawings, and all modifications,
revisions and resubmissions thereof, to (a) be prepared in accordance with
applicable Legal Requirements, including the requirements of the Building
Department of the City of Houston and all other Governmental Authorities, (b) be
consistent in equipment, design and construction with the Building and its
standards, and (c) bear the seals of professionals duly licensed in the State of
Texas.

                                       13
<PAGE>

      5. Tenant shall obtain the prior consent of Landlord as to Tenant's
general contractor (the "General Contractor") and to all other subcontractors to
be used by Tenant in the construction of Tenant's Initial Improvements. Landlord
shall approve or specify reasons for any failure to approve the General
Contractor within three (3) Business Days of Tenant's submission of the
qualifications of the General Contractor. Tenant shall employ only those
subcontractors approved by Landlord, in its reasonable discretion, to perform
electrical or sprinkler work in the Leased Premises. Tenant shall pay to
Landlord a construction management fee equal to 5% of the total cost of any
Alteration which shall be paid to Landlord, or Landlord's designee, within ten
(10) days of written demand for payment therefore (except that Tenant shall not
be required to pay any such construction management fee in connection with
Tenant's Initial Improvements). Notwithstanding anything herein to the contrary,
Tenant shall reimburse Landlord, within ten (10) days of written demand for
payment therefor, for all third-party costs incurred by Landlord in connection
with its review and approval of Tenant's Initial Improvements hereunder. As of
the date hereof, Landlord agrees that the following contractors are hereby
deemed approved general contractors in connection with the performance of
Tenant's Initial Improvements: Cadence McShane, Constructors, J.E. Dunn, Spaw
Maxwell, Tellepsen, Total Interiors, D.E. Harvey and W.S. Bellows.

                       PART II - CONSTRUCTION OBLIGATIONS

      1. Tenant shall administer the construction of the Initial Improvements
with due diligence in accordance with the approved Tenant Working Drawings
labeled by Tenant as "issued for construction" and otherwise in accordance with
standards applicable to Comparable Buildings. The Initial Improvements shall be
constructed by the General Contractor, with the understanding that the General
Contractor shall have the right to have all or any portion of the Initial
Improvements performed by one or more subcontractors. Tenant shall cause to be
prepared all drawings necessary for submission to the Department of Buildings,
City of Houston (or other applicable Governmental Authority) in connection with
the issuance of a building permit for the Initial Improvements. Tenant shall
cause the General Contractor to file for and obtain such building permit.
Landlord agrees to reasonably cooperate with Tenant, at Tenant's sole cost and
expense, in connection with its application for such building permit, including,
without limitation, execution of any documents requiring Landlord's signature
with respect thereto.

      2. Landlord and Tenant shall each designate a person who shall serve as
its representative during construction. Tenant's representative shall provide
administration of the Initial Improvements, and all instructions to Tenant shall
be directed by Landlord's representative to Tenant's representative.

      3. Tenant shall at its sole cost and expense, pay all costs of performing
the Initial Improvements, including all taxes, insurance, permitting,
application fees and expenses related thereto without any additional charge by
Landlord or Landlord's property manager except as otherwise provided under the
Lease.

                                       14
<PAGE>

      4. Tenant may make changes in the Initial Improvements by submitting a
signed change request accompanied by the required revised Tenant Working
Drawings. Within 10 Business Days after Landlord's receipt of the signed change
authorization and revised Tenant Working Drawings from Tenant, Landlord shall
notify Tenant if such changes are approved, which approval shall not be
unreasonably withheld, conditioned or delayed. If Landlord has not notified
Tenant of its approval or disapproval of such changes within such 10 Business
Day period, and provided that such request for approval expressly includes the
following text in BOLD CAPITAL LETTERING "LANDLORD'S APPROVAL OF THE ATTACHED
TENANT WORKING DRAWINGS SHALL BE DEEMED APPROVED IF LANDLORD DOES NOT RESPOND TO
THIS REQUEST WITHIN 10 BUSINESS DAYS HEREOF", then the revised Tenant Working
Drawings shall be deemed approved as submitted to Landlord. If Landlord
discovers a conflict between the Tenant Working Drawings and the plans and
specifications for the Building, then Landlord shall notify Tenant. Tenant shall
thereupon resolve said conflict (with any changes to the Initial Improvements
required thereby being governed by this Section 4, and any delays in completing
the Initial Improvements due to said conflict constituting a Tenant Delay in
accordance with Section 6 below). Tenant shall be responsible for all directions
given to the General Contractor by the Tenant Architect, Tenant's representative
or any of Tenant's consultants. After submission to Landlord of the Tenant
Working Drawings labeled by Tenant as "issued for construction", no change or
addition made by Tenant in the Initial Improvements shall be taken into account
for purposes of determining the date that the substantial completion of the
Initial Improvements occurs, and each such change or addition shall (to the
extent that it extends the time of completion of Initial Improvements)
constitute a Tenant Delay.

      5. Not later than ten (10) Business Days prior to substantial completion
of the Initial Improvements, Tenant shall cause the Tenant Architect to prepare
a final "punch list" which identifies (a) incomplete construction, and (b)
construction completed which is inconsistent with the approved Tenant Working
Drawings labeled by Tenant as "issued for construction" and provide Landlord
with said list, and Tenant shall thereafter complete or cause to be completed
the work properly shown on said list with reasonable diligence.

      6. The Initial Improvements shall be deemed to be substantially complete
on the date that the Initial Improvements would have been substantially complete
but for the occurrence of Tenant Delays. As used herein, the term "Tenant Delay"
means any delay of the nature expressly described herein, and any delay which
Landlord may encounter in the performance of Landlord's obligations in respect
of the performance of the Initial Improvements by reason of any act or omission
of any nature of Tenant, its agents or contractors, including, without
limitation, delay in the submissions of information on or before the dates
specified in Part I above; delays by Tenant in submission of information or
giving authorizations or approvals; delays due to the postponement of any
Initial Improvements at the request of Tenant; provided, however, that no such
delay shall constitute a Tenant Delay if Tenant, using reasonable prudence and
diligence, but without additional expense, could not avoid such delay, and no
such delay shall constitute Tenant Delay unless such delay occurs, or if it has
already occurred to the extent it occurs, after Tenant gives Landlord notice of
the occurrence or possible occurrence thereof and of Tenant's estimate of the
period of such delay.

                                       15
<PAGE>

      7. Subject to the rights of other parties, Landlord acknowledges that
Tenant shall have reasonable access to that portion of the Leased Premises not
currently demised to Tenant pursuant to the 1981 Lease to the extent appropriate
during regular working hours for the purpose of performing any elements of the
Initial Improvements to be performed therein. Tenant shall not have the right to
enter upon such portion of the Leased Premises prior to the Commencement Date as
contemplated by this Section 7 unless Tenant gives Landlord at least three (3)
Business Days' advance notice thereof. Tenant's entry upon such portion of the
Leased Premises prior to the Commencement Date shall be subject to all of the
provisions of the Lease, as amended hereby, except that Tenant shall not be
required to pay Rent for such portion of the Leased Premises by reason of
Tenant's entry upon such portion of the Leased Premises as contemplated by this
Section 7.

      8. Except to the extent otherwise provided in Section 6 hereof, the
Initial Improvements shall not be deemed to be substantially complete unless (I)
the Initial Improvements are substantially complete in substantial conformity
with the Tenant Working Drawings (as theretofore amended in accordance with
Section 4 above), and (II) the governmental permits (if any) required for
Tenant's occupancy thereof have been issued (it being understood that the
incompletion of insubstantial items of the Initial Improvements that does not
interfere in any material respect with Tenant's use and occupancy of the Leased
Premises shall not prevent the Initial Improvements from being considered
substantially complete).

      9. All Initial Improvements shall be performed in accordance with the
rules and regulations established by Landlord from time to time.

      10. Landlord acknowledges that there may be as many as 110 employees of
Tenant, or other persons affiliated with Tenant, working or situated within any
floor of the Lease Premises, other than Levels Bl, B2, 2, 3 or 65, so long as
Tenant complies with all applicable fire safety and other building code
regulations, ordinances or laws that affect permissible building occupancy.

                                       16
<PAGE>

                                   SCHEDULE 5

                           APPROVED ROOFTOP EQUIPMENT

<TABLE>
<CAPTION>
QUANTITY                         APPROVED EQUIPMENT
--------                         ------------------
<S>               <C>
   one            East Face: 4' Dish, 11 GHz Spread Spectrum

   one            East Face: 6' HP Dish - Andrew T6M08J

   one            North Face: 8' Dish, 6.655 GHz - 60.3 Watts (EIRP)

   one            North Face: 8' Dish, 6.315 GHz - 60 Watts (EIRP)

   one            North Face: Wire Dipole Rx only, 5.0; 10.0; 15.0; MHz

   one            North Face: Vertical, 48.74 MHz FM - 100 Watts (EIRP)

   one            South Face: 8' Dish

   one            South Face: 3' Dish - BTV - DSS - 2.3GHz Rx only

   one            South Face: 10' HP Dish

   one            South Face: 18" Steel Whip Antenna mounted on inspection
                  plate -900 MHz

   one            West Face: 1 2 ' HP Dish - Andrew KD12F-22T207C 5.8 GHz
                  Spread Spectrum

     -            Associated antenna standards and cabling for above listed
                  items.
</TABLE>

                                       17
<PAGE>

                                   SCHEDULE 6

                              BASE ROOFTOP RENTAL

<TABLE>
<CAPTION>
                                                   MOUNT OF BASE
LEASE                  PERIOD                      ROOFTOP RENTAL
YEAR           (BOTH DATES INCLUSIVE)               (PER MONTH)
----           ----------------------              --------------
<S>      <C>                                       <C>
  1      March 30, 2004 through March 29, 2005       $1,287.50
  2      March 30, 2005 through March 29, 2006       $1,326.25
  3      March 30, 2006 through March 29, 2007       $1,366.25
  4      March 30, 2007 through March 29, 2008       $2,814.50
  5      March 30, 2008 through March 29, 2009       $   2,899
  6      March 30, 2009 through March 29, 2010       $   2,986
  7      March 30, 2010 through March 29, 2011       $   3,076
  8      March 30, 2011 through March 29, 2012       $3,168.50
  9      March 30, 2012 through March 29, 2013       $3,263.50
 10      March 30, 2013 through March 29, 2014       $3,361.50
</TABLE>

                                       18
<PAGE>

                                   SCHEDULE 7

                               CONTRACTION PAYMENT

The term Contraction Payment means an amount equal to the sum of the following:

            (a) an amount equal to the product of (i) a fraction, the numerator
      of which is the Net Rentable Area of the Contracted Portion of the Leased
      Premises and the denominator of which is the Net Rentable Area of the
      Leased Premises (without taking into account such contraction) (which
      shall initially mean 217,595 square feet, i.e., 21,985 divided by 217,595
      square feet) multiplied by (ii) the unamortized value of the sum of (1) an
      amount equal to (x) the amount of the Base Rental Credit applied prior to
      the Contraction Date less (y) the product of $2.00 multiplied by the
      number of years (any faction thereof) in the Term prior to the Contraction
      Date and (2) any commissions paid by Landlord in connection with this
      Lease; such value shall be calculated based upon (I) an amortization
      period equal to the Term and (II) an annual interest rate equal to (a) 8%
      compounded monthly with respect to commissions and (b) 0% with respect to
      the excess of the Base Rental Credit calculated in accordance with
      subsection (1) above; plus

            (b) an amount equal to the product of (i) the excess of $14.00 over
      the average Base Rental paid during the period commencing on the
      Commencement Date and ending on the Contraction Date (both dates
      inclusive, such period being the "Contraction Period") (such number shall
      be calculated based upon the number of days during such rental periods and
      shall be represented as an annual amount per square foot) multiplied by
      (ii) 21,985 multiplied by (iii) a fraction, the numerator of which is the
      number of days in the Contraction Period and the denominator of which is
      365 (or 366 for leap years).

Based upon the foregoing formula, the Contraction Payment is equal to the
following:

<TABLE>
<CAPTION>
  CONTRACTION DATE
(BOTH DATES INCLUSIVE)                       AMOUNT OF CONTRACTION PAYMENT
----------------------                       -----------------------------
<S>                                          <C>
March 30, 2007 - March 31, 2007                      $ 378,867
April 1, 2007 - April 30, 2007                         399,651
May 1, 2007 - May 31, 2007                             398,466
June 1,2007 - June 30,2007                             397,236
July 1,2007 - July 31,2007                             396,023
August 1, 2007 - August 31, 2007                       394,795
September 1, 2007 - September 30, 2007                 393,523
October 1, 2007 - October 31, 2007                     392,266
November 1, 2007 - November 30, 2007                   390,965
December 1 , 2007 - December 31 , 2007                 389,679
</TABLE>

                                       19
<PAGE>

<TABLE>
<CAPTION>
CONTRACTION DATE
(BOTH DATES INCLUSIVE)                       AMOUNT OF CONTRACTION PAYMENT
----------------------                       -----------------------------
<S>                                          <C>
January 1 , 2008 - January 31 , 2008                   388,263
February 1, 2008 - February 29, 2008                   386,884
March 1, 2008 - March 31, 2008                         385,551
April 1, 2008 - April 30, 2008                         384,173
May 1,2008 - May 31,2008                               382,809
June 1, 2008 - June 30, 2008                           381,400
July 1,2008 - July 31,2008                             380,006
August 1 , 2008 - August 31 , 2008                     378,596
September 1, 2008 - September 30, 2008                 377,141
October 1, 2008 - October 31, 2008                     375,700
November 1, 2008 - November 30, 2008                   374,213
December 1, 2008 - December 31, 2008                   372,740
January 1, 2009 - January 31, 2009                     371,397
February 1, 2009 - February 28, 2009                   369,804
March 1, 2009 - March 31, 2009                         368,286
April 1, 2009 - April 30, 2009                         364,914
May 1,2009 - May 31,2009                               361,495
June 1,2009 - June 30, 2009                            358,090
July 1,2009 - July 31,2009                             354,638
August 1, 2009 - August 31, 2009                       351,169
September 1, 2009 - September 30, 2009                 347,714
October 1, 2009 - October 31, 2009                     344,211
November 1, 2009 - November 30, 2009                   340,722
December 1, 2009 - December 31, 2009                   337,185
January 1, 2010 - January 31, 2010                     333,630
February 1, 2010 - February 28, 2010                   330,149
March 1, 2010 - March 31, 2010                         326,560
April 1,2010 - April 30, 2010                          300,998
May 1,2010 - May 31, 2010                              297,373
June 1,2010 - June 30, 2010                            293,760
July 1,2010 - July 31, 2010                            290,099
August 1, 2010 - August 31, 2010                       286,420
September 1, 2010 - September 30, 2010                 282,753
October 1 , 2010 - October 31 , 2010                   279,037
November 1, 2010 - November 30, 2010                   275,333
</TABLE>

                                       20
<PAGE>

<TABLE>
<CAPTION>
CONTRACTION DATE
(BOTH DATES INCLUSIVE)                       AMOUNT OF CONTRACTION PAYMENT
----------------------                       -----------------------------
<S>                                          <C>
December 1, 2010 - December 31, 2010                    271,580
January 1, 2011 - January 31, 2011                      267,808
February 1, 2011 - February 28, 2011                    264,107
March 1, 2011 - March 31, 2011                          260,298
April 1, 2011 - April 30, 2011                          234,514
May 1, 2011 - May 31, 2011                              230,666
June 1, 2011 - June 30, 2011                            226,828
July 1, 2011 - July 31, 2011                            222,941
August 1, 2011 - August 31, 2011                        219,034
September 1, 2011 - September 30, 2011                  215,137
October 1, 2011 - October 31, 2011                      211,190
November 1, 2011 - November 30, 2011                    207,254
December 1, 2011 - December 31, 2011                    203,267
January 1, 2012 - January 31, 2012                      200,201
February 1, 2012 - February 29, 2012                    196,243
March 1, 2012 - March 31, 2012                          192,205
April 1, 2012 - April 30, 2012                          144,205
May 1, 2012 - May 31, 2012                              140,125
June 1, 2012 - June 30, 2012                            136,054
July 1, 2012 - July 31, 2012                            131,932
August 1, 2012 - August 31, 2012                        127,788
September 1, 2012 - September 30, 2012                  123,653
October 1, 2012 - October 31, 2012                      119,467
November 1, 2012 - November 30, 2012                    115,288
December 1, 2012 - December 31, 2012                    111,058
January 1, 2013 - January 31, 2013                      105,743
February 1, 2013 - February 28, 2013                    101,549
March 1, 2013 - March 31, 2013                           97,242
April 1, 2013 - April 30, 2013                           48,972
May 1, 2013 - May 31, 2013                               44,620
June 1, 2013 - June 30, 2013                             40,275
July 1, 2013 - July 31, 2013                             35,877
August 1, 2013 - August 31, 2013                         31,456
September 1, 2013 - September 30, 2013                   27,042
October 1, 2013 - October 31, 2013                       22,574
November 1, 2013 - November 30, 2013                     18,113
December 1, 2013 - December 31, 2013                     13,598
January 1, 2014 - January 31, 2014                        9,060
February 1, 2014 - February 28, 2014                      4,587
March 1, 2014 - March 29, 2014                                -
</TABLE>

                                       21
<PAGE>

                                   SCHEDULE 8

                              TERMINATION PAYMENT

The term Termination Payment means an amount equal to the sum of the following:

            (a) the unamortized value of $543,988 (representing $2.50 x 217,595
      square feet), decreased by the amount, if any, determined pursuant to
      Schedule 7, Paragraph (b) and previously paid by Tenant to Landlord in
      connection with a previous exercise of the Contraction Option plus

            (b) $1,305,570 (representing $1.20 x 5 x 217,595 square feet),
      decreased by the amount, if any, determined pursuant to Schedule 7,
      Paragraph (b) and previously paid by Tenant to Landlord in connection with
      a previous exercise of the Contraction Option Plus

            (c) any commissions paid by Landlord in connection with this Lease;
      such value shall be calculated based upon (I) an amortization period equal
      to the Term and (II) an annual interest rate equal to 8% compounded
      monthly.

Based upon the foregoing formula, the Termination Payment is equal to the
following:

<TABLE>
<CAPTION>
                                    AMOUNT OF TERMINATION PAYMENT        AMOUNT OF TERMINATION PAYMENT
                                    ASSUMING TENANT HAS EXERCISED      (ASSUMING TENANT HAS NOT EXERCISED
        TERMINATION DATE                THE CONTRACTION OPTION               THE CONTRACTION OPTION
(EFFECTIVE DATE): MARCH 29, 2009          UNDER SECTION 1.03)                 UNDER SECTION 1.03)
--------------------------------    ------------------------------     ----------------------------------
<S>                                 <C>                                <C>
CONTRACTION PAYMENT DATE:
 March 30,     March 31,
      2007         2007                     $  3,806,133                         $  4,179,258
  April 1,     April 30,
      2007         2007                        3,764,518
    May 1,      May 31,
      2007         2007                        3,744,733
   June 1,     June 30,
      2007         2007                        3,724,853
   July 1,     July 31,
      2007         2007                        3,704,816
 August 1,   August 31,
      2007         2007                        3,684,651
</TABLE>

                                       22
<PAGE>

<TABLE>
<CAPTION>
                                        AMOUNT OF TERMINATION PAYMENT           AMOUNT OF TERMINATION PAYMENT
                                        (ASSUMING TENANT HAS EXERCISED            (ASSUMING TENANT HAS NOT
        TERMINATION DATE                 THE CONTRACTION OPTION UNDER         EXERCISED THE CONTRACTION OPTION
(EFFECTIVE DATE): MARCH 29, 2009                 SECTION 1.03)                      UNDER SECTION 1.03)
--------------------------------        ------------------------------        ----------------------------------
<S>                                     <C>                                   <C>
CONTRACTION PAY MENT DATE:
September 1,  September 30,
        2007          2007                         3,664,389
  October 1,   October 31,
        2007          2007                         3,643,967
 November 1,  November 30,
        2007          2007                         3,623,446
 December 1,  December 31,
        2007          2007                         3,602,763
  January 1,   January 31,
        2008          2008                         3,582,065
 February 1,  February 29,
        2008          2008                         3,561,181
    March 1,     March 31,
        2008          2008                         3,540,103
    April 1,     April 30,
        2008          2008                         3,518,922
      May 1,       May 31,
        2008          2008                         3,497,575
     June 1,      June 30,
        2008          2008                         3,476,122
     July 1,      July 31,
        2008          2008                         3,454,502
   August 1,    August 31,
        2008          2008                         3,432,744
September 1, September 30,
        2008          2008                         3,410,877
</TABLE>

                                       23
<PAGE>

<TABLE>
<CAPTION>
                                                  AMOUNT OF                             AMOUNT OF
                                            TERMINATION PAYMENT                    TERMINATION PAYMENT
                                       (ASSUMING TENANT HAS EXERCISED           (ASSUMING TENANT HAS NOT
        TERMINATION DATE                   THE CONTRACTION OPTION            EXERCISED THE CONTRACTION OPTION
(EFFECTIVE DATE): MARCH 29, 2009             UNDER SECTION 1.03)                   UNDER SECTION 1.03)
--------------------------------       ------------------------------        --------------------------------
<S>                                    <C>                                   <C>
CONTRACTION PAYMENT DATE:
  October 1,   October 31,
        2008          2008                        3,388,840
 November 1,  November 30,
        2008          2008                        3,366,693
 December 1,  December 31,
        2008          2008                        3,344,374
  January 1,   January 31,
        2009          2009                        3,321,767
 February 1,  February 28,
        2009          2009                        3,299,250
    March 1,     March 31,
        2009          2009                        3,276,498
</TABLE>

                                       24
<PAGE>

                                   SCHEDULE 9

                              JANITORIAL SERVICES

<TABLE>
<CAPTION>
A. SERVICE AREAS                                                                D     W     M     Q     S-A
----------------                                                               ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Keep waste paper, cardboard, rubbish, etc., stored in approved
  receptacles or assigned rooms.                                                X
Clean floors, walls and doors, etc., as necessary.                              X
Dust all pipes, ducts, ventilating grilles, air conditioning and other
  accessible equipment outside the machinery spaces.                                              X
Clean all janitor closets at the end of each shift.                             X
Clean around compactor area and service dock.                                         X
Perform special assignments as requested.
</TABLE>

<TABLE>
<CAPTION>
B. EXTERIORS AND ENTRANCES                                                      D     W     M     Q     S-A
---------------------------                                                    ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Police and/or sweep entrance areas and sidewalks adjacent to the building.
  Damp mop stains and spills.                                                   X
Clean door glass and frames.                                                    X
Wipe down horizontal entrance ledges.                                                       X
Remove gum or other adhesive material.                                          X
Wet mop or flush clean exterior entrances.                                            X
Clean all metal finishes at entrances.                                                      X
Extract dirt and grime from entrance walk off mats                                    X
</TABLE>

<TABLE>
<CAPTION>
C. ENTRANCE LOBBIES/CORRIDORS                                                   D     W     M     Q     S-A
------------------------------                                                 ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Dust mop and wet mop all flooring as appropriate.                               X
Vacuum carpets completely.                                                      X
Clean coffee table and chairs.                                                        X
Dust all ledges within reach.                                                   X
Dust all wood paneling.                                                               X
Dust concierge's desk.                                                          X
Empty and wash cigarette/trash receptacles, replace sand as necessary.                X
Clean elevator doors as needed.                                                       X
Spot clean walls and doors.                                                                 X
Clean entrance door glass.                                                      X
Clean directory board glass.                                                          X
Vacuum entrance mats                                                            X
Extract entrance mats.                                                                X
Clean all metal at entrances and other areas of lobby.                                X
Clean and polish drinking fountains.                                            X
Vacuum ceiling tiles adjacent to ceiling vents.                                                   X
</TABLE>

                                       25
<PAGE>

<TABLE>
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Spot clean carpet.                                                              X
Matching polish and/or apply finish to all non-carpeted areas.                        X
Clean all light fixtures.                                                                         X
Clean public telephone area.                                                    X
Clean common corridor carpets; extraction.                                                        X
</TABLE>

<TABLE>
<CAPTION>
D. RESTROOMS                                                                    D     W     M     Q     S-A
------------                                                                   ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Clean, sanitize, wipe dry all porcelain fixtures.                               X
Clean and polish all chrome faucets and fixtures with an approved product.      X
Clean mirrors and frames.                                                       X
Empty waste containers.                                                         X
Wash waste containers.                                                                      X
Sanitize toilets, both sides of toilet seats, urinals and sanitary napkin
  receptacles.                                                                  X
Dust ledges and partitions.                                                     X
Wet mop floors with disinfecting cleaning.                                      X
Machine scrub floors and wax as necessary.                                                  X
Spot clean walls, partitions, ledges, sills, counters and doors.                      X
Wash/sanitize all walls, partitions.                                                  X
Wash counter tops.                                                              X
Refill all towel, tissue, soap and neat seat dispensers.                        X
Vacuum ceiling vents and ceiling tiles adjacent to vents.                                   X
Perform high dusting, including walls.                                                X
Clean all light fixtures.                                                                                X
Fill floor drains with water and disinfectant.                                        X
</TABLE>

<TABLE>
<CAPTION>
E. ELEVATORS                                                                    D     W     M     Q     S-A
------------                                                                   ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Vacuum and clean carpeting daily.                                               X
Wipe doors, frames, walls, saddles and tracks.                                  X
Spot shampoo carpet as necessary.                                               X
Clean ceilings and grilles.                                                     X
Clean light fixtures.                                                           X
Dust all wood panels.                                                           X
</TABLE>

<TABLE>
<CAPTION>
F. STAIRWAYS                                                                    D     W     M     Q     S-A
------------                                                                   ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Remove debris and spot clean.                                                   X
Sweep completely and dust handrails.                                                  X
Wet mop stairs completely.                                                                  X
Clean light fixtures.                                                                                    X
Clean inside of fire extinguisher cabinets.                                                       X
</TABLE>

                                       26
<PAGE>

<TABLE>
<CAPTION>
G. DRINKING FOUNTAINS                                                           D     W     M     Q     S-A
---------------------                                                          ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Fixtures will be cleaned, sanitized and polished to remove                      X
stains, rust and scale with an approved product.
</TABLE>

<TABLE>
<CAPTION>
F. TENANT AREAS                                                                 D     W     M     Q     S-A
---------------                                                                ---   ---   ---   ---   -----
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Waste receptacles: empty and replace plastic liner as necessary and
transport all trash to compactor.                                               X
Return waste receptacles to original location.                                  X
Wash out waste receptacles.                                                                 X
Dust mop resilient tile floors with chemically treated dust mops.               X
Damp mop resilient tile floors.                                                       X
Strip, apply finish and buff resilient tile floors.                                         X
Vacuum carpet in usage areas.                                                   X
Vacuum carpeted areas completely, including edges.                                    X
Vacuum upholstered furniture.                                                               X
Dust desks, desk accessories, chairs and all other office furniture.            X
Dust all ledges and flat surfaces within reach.                                 X
Dust all baseboards.                                                                  X
Dust all vertical surfaces on furniture and spot clean.                               X
Dust all door louvers and other ventilation louvers within reach.                     X
Dust all doors.                                                                       X
Perform low dusting not done daily.                                                   X
Perform high dusting - i.e. door sash, tips of partitions, etc.                             X
Dust picture frames and other wall hangings.                                                X
Dust or vacuum all air vents and ceiling tiles adjacent to air vents.                       X
Dust all Venetian blinds.                                                                   X
Dust walls, doors and other surfaces not dusted on monthly basis.                                 X
Clean glass desk tops.                                                          X
Spot clean doors, door frames, desk tops and counter tops.                      X
Spot clean around wall switches.                                                X
Spot clean partition door glass.                                                X
Spot clean spillage from tile floors.                                           X
Remove finger smudges and soil from woodwork, walls, etc.                             X
Upon completion of cleaning in an area, all lights are turned off.              X
Check and lock all doorways as instructed by Manager                            X
Properly position furniture, magazines, waste baskets, etc.                     X
Clean and polish drinking fountains.                                            X
Pile lift carpeting.                                                                              X
Lift chair pads and vacuum or clean as needed.                                                    X
Clean all light fixtures.                                                                                X
Apply finish and machine polish all non-carpeted areas.                                                  X
</TABLE>

                                       27
<PAGE>

<TABLE>
<S>                                                                            <C>   <C>   <C>   <C>   <C>
Clean sinks, table tops, counter tops, outside of appliances and trash
receptacles in kitchen areas.                                                   X
</TABLE>

                                       28
<PAGE>

                                    EXHIBIT A

                          FLOOR PLAN OF LEASED PREMISES

                                       29
<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL B2

                                 WILLIAMS TOWER

<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL B1

                                 WILLIAMS TOWER

<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL 2

                                 WILLIAMS TOWER

<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL 3

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 9

                                 (NRA - 21,954)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 10

                                 (NRA - 21,968)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 11

                                 (NRA - 21,968)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 12

                                 (NRA - 21,968)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 13

                                 (NRA - 21,968)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 14

                                 (NRA - 21,968)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 15

                                 (NRA - 21,974)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 16

                                 (NRA - 21,985)

                                 WILLIAMS TOWER

<PAGE>

                                    WILLIAMS

                                  [FLOOR PLAN]

                                    LEVEL 17

                                 (NRA - 21,985)

                                 WILLIAMS TOWER

<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL 65

                                 WILLIAMS TOWER

<PAGE>

                                    EXHIBIT B

                                LAND DESCRIPTION

TRACT ONE

      FIELD NOTE DESCRIPTION of a tract or parcel of land containing 6.6991
acres situated in the William White 1/3 League, Abstract No. 836 in Harris
County, Texas. Said 6.6991 acre tract being more particularly described by metes
and bounds as follows:

      COMMENCING at the point of intersection of the extended Southerly
right-of-way line of West Alabama (60-foot wide right-of-way) with the extended
Westerly right-of-way line of South Post Oak Road (100-foot wide right-of-way);

      THENCE, South 02 degrees 41'32" East, along the extended Westerly
right-of-way line of South Post Oak Road, for a distance of 10.00 feet to a
5/8-inch iron rod found for corner at the POINT OF BEGINNING of the herein
described 6.6991 acre tract;

      THENCE, South 02 degrees 41'32" East, along the Westerly right-of-way line
of South Post Oak Road, for a distance of 449.18 feet to a 5/8-inch iron rod set
for corner;

      THENCE, South 87 degrees 18'28" West, leaving the Westerly right-of-way
line of South Post Oak Road, for a distance of 534.63 feet to the point of
curvature of a curve to the right;

      THENCE, along said curve to the right, having a central angle of
15 degrees 26'38", a radius of 166.17 feet, an arc length of 44.79 feet, a chord
bears North 84 degrees 58' 13" West, 44.66 feet to a nail and cap set at the
point of reverse curvature of a curve to the left;

      THENCE, along said curve to the left, having a central angle of 15 degrees
26'38", a radius of 166.17 feet, an arc length of 44.79 feet, a chord bears
North 84 degrees 58'13" West, 44.66 feet to a nail and cap set at the point of
tangency of said curve to the left;

      THENCE, South 87 degrees 18'28" West, for a distance of 4.50 feet to a
nail and cap set for corner;

      THENCE, North 02 degrees 41'32" West, for a distance of 456.30 feet to a
"x" cut in concrete set for corner in the Southerly right-of-way line of West
Alabama, said "x" cut in concrete also being in a curve to the left;

      THENCE, along the Southerly right-of-way line of West Alabama and said
curve to the left, having a central angle of 00 degrees 40'10", a radius of
1,774.94 feet, and arc length of 20.74 feet, a chord bears North
87 degrees 55'40" East, 20.74 feet to a 5/8-inch iron rod found at the point of
tangency of said curve to the left;

      THENCE, North 87 degrees 35'35" East, continuing along the Southerly
right-of-way line of West Alabama, for a distance of 468.96 feet to a cross cut
in concrete found at the point of curvature of a curve to the right;

                                       30

<PAGE>
      THENCE, continuing along the Southerly right-of-way line of West Alabama
and said curve to the right having a central angle of 04 degrees 56'20", a
radius of 770.00 feet, an arc length of 66.37 feet, a chord bears South 89
degrees 56'15" East, 66.35 feet to a cross cut in concrete found for corner at
the point of reverse curvature of a curve to the left;

      THENCE, continuing along the Southerly right-of-way line of West Alabama
and said curve to the left having a central angle of 04 degrees 15'43" a radius
of 830.00 feet, an arc length of 61.75 feet, a chord bears South
89 degrees 35'57" East, 61.73 feet to a 5/8-inch iron rod found for corner;

      THENCE, South 47 degrees 36'05" East, leaving the Southerly right-of-way
line of West Alabama, for a distance of 14.18 feet to the POINT OF BEGINNING;
CONTAINING within these metes and bounds 6.6991 acres (291,813 square feet) of
land area.

NOTE: All bearings contained herein are based on the Texas Lambert Grid
Coordinate System, South Central Zone.

TRACT TWO:

      FIELD NOTE DESCRIPTION of a tract or parcel of land containing 2.7786
acres of land situated in the William White 1/3 League, Abstract No. 836, Harris
County, Texas. Said 2.7786 acres being more particularly described by metes and
bounds as follows:

      COMMENCING at the point of intersection of the extended Southerly
right-of-way line of West Alabama (60-foot wide right-of-way) with the extended
Westerly right-of-way line of South Post Oak Road (100-foot right-of-way);

      THENCE, S 02 degrees 41'32" E, along said extended Westerly right-of-way
line of South Post Oak Road at 10.00 feet passing a 5/8-inch iron rod found and,
continuing along said Westerly right-of-way line, for a total distance of 459.18
feet to a 5/8-inch iron rod set at the POINT OF BEGINNING of the herein
described 2.7786 acres;

      THENCE, S 02 degrees 41'32" E, continuing along the Westerly right-of-way
line of South Post Oak Road, for a distance of 200.88 feet to a 5/8-inch iron
rod set for corner;

      THENCE, S 03 degrees  07'22" W, continuing along the Westerly right-of-way
line of South Post Oak Road, for a distance of 95.64 feet (called 100.50') to a
5/8-inch iron rod set for corner;

      THENCE, S 02 degrees 35'16" E, continuing along the Westerly right-of-way
line of South Post Oak Road, for a distance of 100.00 feet to a 5/8-inch iron
rod set at the point of curvature of a curve to the right;

      THENCE, leaving the Westerly right-of-way line of South Post Oak Road and
along said curve to the right having a central angle of 93 degrees 27'13", a
radius of 40.00 feet, an arc length of 65.24 feet, a chord bears S
44 degrees 08'20" W, 58.26 feet to a 5/8-inch rod set at the point of

                                       31

<PAGE>

                                   EXHIBIT C

                              PARKING SPACE RADIUS

                                  [FLOOR PLAN]

                                       33

<PAGE>

                                    EXHIBIT D

                                   ROOF SPACE

                                       34

<PAGE>

                            FIRST AMENDMENT OF LEASE
                      BY AND BETWEEN TRANSCO TOWER LIMITED
                 AND TRANSCONTINENTAL GAS PIPE LINE CORPORATION

      This First Amendment of Lease (the "Amendment") is for reference purposed
dated as of March 10, 2004, but executed as of the date set forth below the
parties' signatures and is made and entered by and between TRANSCO TOWER LIMITED
("Landlord") and TRANSCONTINENTAL GAS PIPE LINE CORPORATION ("Tenant").

                                   WITNESSETH:

      WHEREAS, the following facts currently exist:

      A. A certain Lease Agreement (the "New Lease") was made and entered into
on October 23, 2003 by and between Landlord and Tenant, under the terms of which
Landlord will lease to Tenant certain demised premises in the building known as
the Williams Tower located at 2800 Post Oak Boulevard, Houston, Harris County,
Texas (the "Building");

      B. Tenant currently, pursuant to an existing Lease (the "Existing Lease"),
occupies premises in the Building including 7,769 square feet of Net Rentable
Area (as defined in the New Lease) located on Level 5 of the Building, (the
location of which space is particularly shown on Exhibit A which is attached
hereto and made a part hereof and is herein called the "Level 5 Space"). The
Level 5 Space is currently being used as a nursing and fitness station.

      C. The Existing Lease will expire March 29, 2004, and Tenant and Landlord
have entered into the New Lease which will commence March 30, 2004; however, the
New Lease does not cover or pertain to the Level 5 Space and upon the expiration
of the Existing Lease, Tenant would have no right to occupy the Level 5 Space.

      D. Tenant has requested that Tenant be allowed to continue to lease and
occupy the Level 5 Space after the expiration of the Existing Lease on a
month-to-month basis. Landlord is agreeable to so amending the New Lease to
cover the Level 5 Space under the terms and conditions herein set forth.

      NOW THEREFORE, in consideration of Ten Dollars ($10.00) paid by Tenant to
Landlord, and other good and valuable consideration by each of the parties
hereto to the other, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

      1. The above recitals are hereby incorporated herein for all purposes, and
all terms used herein shall have the same meaning as in the New Lease, except as
otherwise defined herein.

      2. Upon the expiration of the Existing Lease Tenant may continue to occupy
the Level 5 Space as a tenant on a month to month basis with either Landlord or
Tenant having the right to terminate Tenant's occupancy of the Level 5 Space
upon 30 days prior written notice to the other. From and after the Commencement
Date (as defined in the New Lease) of the New

<PAGE>

Lease, the Level 5 Space shall be part of the Leased Premises described in the
New Lease and Tenant shall pay during the period the New Lease is applicable to
the Level 5 Space as Base Annual Rental on a per square foot of Net Rentable
Area (calculated on a monthly basis) the same Base Annual Rental as set forth on
Schedule 2 of the New Lease for each square foot of Net Rentable Area in the
Level 5 Space. All terms and conditions applicable to the Leased Premises under
the New Lease shall be applicable to the Level 5 Space (including, without
limitation, Tenant shall pay all Additional Rent as defined in the New Lease)
except (i) Tenant shall not be entitled to the Base Rental Credit set forth in
Schedule 3 of the New Lease, (ii) the New Lease as to the Level 5 Space may be
terminated as provided above by either party giving the other party 30 days
written notice of termination as to the Level 5 Space, and (iii) Tenant shall
have no renewal option as to the Level 5 Space (and the provisions of Article 6
dealing with renewal of the New Lease shall not apply to the Level 5 Space).

      3. Tenant has heretofore been occupying the Level 5 Space and is familiar
with the same and agrees to and does hereby accept as of the Commencement Date
(as defined in the New Lease) of the New Lease the Level 5 Space "As-Is",
"Where-Is" and "With All Faults" with Landlord having no obligation to make any
renovations or allowance in lieu thereof.

      4. Tenant warrants and represents that it has not dealt with any other
broker or intermediary entitled to any compensation in connection with this
letter agreement or Tenant's occupancy space in the Level 5 Space other than
Named Broker (as defined in the New Lease) which shall be paid a commission by
Landlord pursuant to a separate agreement between Landlord and such broker. Each
party agrees to hold the other party, its partners and representatives harmless
from any and all claims, liabilities, costs and expenses (including reasonable
attorneys' fees) arising from any claim for any commission or other fees by any
other broker or agent acting or purporting to act on behalf of such party other
than the Named Broker.

      Except as amended herein, the New Lease remains unchanged and is in full
force and effect in accordance with the terms and provisions contained therein.

      THIS AMENDMENT IS NOT TO BE CONSTRUED AS BINDING UPON LANDLORD WHETHER
LANDLORD PREPARED OR CAUSED THE SAME TO BE PREPARED AND DELIVERED TO TENANT
UNTIL SUCH TIME AS THE SAME IS EXECUTED BY LANDLORD'S AUTHORIZED REPRESENTATIVE
IN THE SPACE PROVIDED BELOW AND DELIVERED TO TENANT.
<PAGE>

      This Amendment of Lease is hereby executed and delivered in multiple
counterparts, each of which shall have the force and effect of an original.

"LANDLORD"

TRANSCO TOWER LIMITED

By: McCue Street Investors, LLC
    a limited liability company
    Its General Partner

    BY: Eric P. Blanchard
        ------------------------
        Name: Eric P. Blanchard
        Its:  Assistant Treasurer/
              Assistant secretary

    BY: Michael S. Lane
        ------------------------
        Name: Michael S. Lane
        Its:  Vice President, Treasurer
              & secretary

Date Executed: _______________________

"TENANT"

TRANSCONTINENTAL GAS PIPE LINE CORPORATION

By: /s/ [ILLEGIBLE]
    ----------------------------
    Name: [ILLEGIBLE]
    Title: Senior Vice president

Date Executed: 3-25-04

<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL 5

                                 WILLIAMS TOWER

                                  EXHIBIT "A"
<PAGE>

                            SECOND AMENDMENT OF LEASE
                      BY AND BETWEEN TRANSCO TOWER LIMITED
                 AND TRANSCONTINENTAL GAS PIPE LINE CORPORATION

      This Second Amendment of Lease (the "Amendment") is for reference purposed
dated as of March 11, 2004, but executed as of the date set forth below the
parties' signatures and is made and entered by and between TRANSCO TOWER LIMITED
("Landlord") and TRANSCONTINENTAL GAS PIPE LINE CORPORATION ("Tenant").

                                   WITNESSETH:

      WHEREAS, the following facts currently exist:

      A.    A certain Lease Agreement (the "Original New Lease") was made and
entered into on October 23, 2003 by and between Landlord and Tenant, under the
terms of which Landlord will lease to Tenant certain demised premises in the
building known as the Williams Tower located at 2800 Post Oak Boulevard,
Houston, Harris County, Texas (the "Building"); the New Lease was amended by
First Amendment ("First Amendment") dated for reference purposes as of March 10,
2004, to incorporate space on Level 5 of the Building into the Original New
Lease. The Original New Lease, as amended by the First Amendment, is herein
called the "New Lease".

      B.    Tenant currently, pursuant to an existing Lease (the "Existing
Lease"), occupies premises in the Building including 23,090 square feet of Net
Rentable Area (as defined in the New Lease) located on Level 36 of the
Building, (the location of which space is particularly shown on Exhibit A which
is attached hereto and made a part hereof and is herein called the "Level 36
Space"). The Level 36 Space has been occupied by an affiliate of Tenant,
Williams Field Services Company ("Services").

      C.    The Existing Lease will expire March 29, 2004, and Tenant and
Landlord have entered into the New Lease which will commence March 30, 2004;
however, the New Lease does not cover or pertain to the Level 36 Space and upon
the expiration of the Existing New Lease, Tenant would have no right to occupy
the Level 36 Space.

      D.    Tenant has requested that Tenant be allowed to continue to lease and
for Tenant or Services to occupy the Level 36 Space after the expiration of the
Existing Lease through June 27, 2004. Landlord is agreeable to so amending the
New Lease to cover the Level 36 Space under the terms and conditions herein set
forth.

      NOW THEREFORE, in consideration of Ten Dollars ($10.00) paid by Tenant to
Landlord, and other good and valuable consideration by each of the parties
hereto to the other, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows;

<PAGE>

      1.    The above recitals are hereby incorporated herein for all purposes,
and all terms used herein shall have the same meaning as in the New Lease,
except as otherwise defined herein.

      2.    Upon the expiration of the Existing Lease Tenant may continue to
occupy the Level 36 Space through June 27, 2004 with Tenant having the right to
terminate the New Lease as it pertains to the Level 36 Space upon 30 days prior
written notice to the Landlord. From and after the Commencement Date (as defined
in the New Lease) of the New Lease, the Level 36 Space shall be part of the
Leased Premises described in the New Lease and Tenant shall pay during the
period the New Lease is applicable to the Level 36 Space as Base Annual Rental
on a per square foot of Net Rentable Area (calculated on a monthly basis) the
same Base Annual Rental as set forth on Schedule 2 of the New Lease for each
square foot of Net Rentable Area in the Level 36 Space. All terms and
conditions applicable to the Leased Premises under the New Lease shall be
applicable to the Level 36 Space (including, without limitation, Tenant shall
pay all Additional Rent as defined in the New Lease) except (i) Tenant shall not
be entitled to the Base Rental Credit set forth in Schedule 3 of the New Lease,
(ii) the New Lease as to the Level 36 Space may be terminated as provided above
by Tenant giving Landlord 30 days written notice of termination as to the Level
36 Space, and if no earlier terminated, the New Lease shall terminate as to the
Level 36 Space on June 27, 2004, and (iii) Tenant shall have no renewal option
as to the Level 36 Space (and the provisions of Article 6 dealing with renewal
of the New Lease shall not apply to the Level 36 Space).

      3.    Landlord expressly consents to services occupying the Level 36
Space; however, Tenant shall be the tenant of the Level 36 Space and be
responsible for all obligations under the New Lease with respect to the same.
Services by executing this Amendment is evidencing Services' agreement to the
provisions hereof and to evidence that Services agrees to vacate the Level 36
Space upon the expiration of the New Lease as to the Level 36 Space however the
same may be brought about

      4.    Tenant and Services have heretofore been occupying the Level 36
Space and they are familiar with the same and Tenant and Services agree to and
do hereby accept as of the Commencement Date (as defined in the New Lease) of
the New Lease the Level 36 Space "As - Is", "Where-Is" and "With All Faults"
with Landlord having no obligation to make any renovations or allowance in lieu
thereof.

      5.    Tenant warrants and represents that it has not dealt with any other
broker or intermediary entitled to any compensation in connection with this
letter agreement or Tenant's occupancy space in the Level 36 Space and will
occupy Level 36 Space "As - Is", "Where-Is" and "With All Faults" other than
Named Broker (as defined in the New Lease) which shall be paid a commission by
Landlord pursuant to a separate agreement between Landlord and such broker. Each
party agrees to hold the other party, its partners and representatives harmless
from any and all claims, liabilities, costs and expenses (including reasonable
attorneys' fees) arising from any claim for any commission or other fees by any
other broker or agent acting or purporting to act on behalf of such party other
than the Named Broker.

                                       2
<PAGE>

      Except as amended herein, the New Lease remains unchanged and is in full
force and effect in accordance with the terms and provisions contained therein.

      THIS AMENDMENT IS NOT TO BE CONSTRUED AS BINDING UPON LANDLORD WHETHER
LANDLORD PREPARED OR CAUSED THE SAME TO BE PREPARED AND DELIVERED TO TENANT
UNTIL SUCH TIME AS THE SAME IS EXECUTED BY LANDLORD'S AUTHORIZED REPRESENTATIVE
IN THE SPACE PROVIDED BELOW AND DELIVERED TO TENANT.

      This Amendment of Lease is hereby executed and delivered in multiple
counterparts, each of which shall have the force and effect of an original.

"LANDLORD"

TRANSCO TOWER LIMITED

By: McCue Street Investors, LLC
    a limited liability company
    Its General Partner

    By: /s/ Eric P. Blanchard
        -------------------------
        Name: Eric P. Blanchard
        Its: Assistant Treasurer/
             Assistant secretary

    By: /s/ Michael S. Lane
        -------------------------
        Name: Michael S. Lane
        Its: Vice President, Treasurer
             & secretary

DATE Executed ______________________

"TENANT"

TRANSCONTINENTAL GAS PIPE LINE CORPORATION

By: /s/ [ILLEGIBLE]
    -----------------------------
    Name: [ILLEGIBLE]
    Title: Senior Vice President

Date Executed: 3-25-04

                                       3
<PAGE>

AGREED AND ACCEPTED BY WILLIAMS
FIELD SERVICES COMPANY, this 25th day of
MARCH, 2004:

WILLIAM FIELD SERVICES COMPANY

By: /s/ [ILLEGIBLE]
    -----------------------------
    Name: [ILLEGIBLE]
    Title: VP

                                        4
<PAGE>

                                  [FLOOR PLAN]

                                    LEVEL 36

                                  [NRA-23,090]

                                 WILLIAMS TOWER
<PAGE>

                            THIRD AMENDMENT OF LEASE
                      BY AND BETWEEN TRANSCO TOWER LIMITED
                 AND TRANSCONTINENTAL GAS PIPE LINE CORPORATION

      This Third Amendment of Lease (the "Amendment") is for reference purposed
dated as of May 10, 2004, but executed as of the date set forth below the
parties' signatures and is made and entered by and between TRANSCO TOWER LIMITED
("Landlord") and TRANSCONTINENTAL GAS PIPE LINE CORPORATION ("Tenant").

                                   WITNESSETH:

      WHEREAS, the following facts currently exist:

      A.    A certain Lease Agreement (the "Original New Lease") was made and
entered into on October 23, 2003 by and between Landlord and Tenant, under the
terms of which Landlord leased to Tenant certain demised premises in the
building known as the Williams Tower located at 2800 Post Oak Boulevard,
Houston, Harris County, Texas (the "Building"); the New Lease was amended by (i)
First Amendment of Lease ("First Amendment") dated for reference purposes as of
March 10, 2004, to incorporate space on Level 5 of the Building into the
Original New Lease, and (ii) Second Amendment of Lease ("Second Amendment")
dated for reference purposes as of March 11, 2004, to incorporate space on Level
36 of the Building into the Original New Lease and an Extension of Second
Amendment of Lease dated as of June 25, 2004 ("Extension"). The Original New
Lease, as amended by the First Amendment, Second Amendment and the Extension, is
herein called the "New Lease".

      B.    Tenant now desires to lease additional space on Level 8 of the
Building and Landlord is agreeable to so amending the New Lease to add such
space to the Lease under the terms and conditions herein set forth.

      NOW THEREFORE, in consideration of Ten Dollars ($10.00) paid by
Tenant to Landlord, and other good and valuable consideration by each of the
parties hereto tO the other, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

      1.    The above recitals are hereby incorporated herein for all purposes,
and all terms used herein shall have the same meaning as in the New Lease,
except as otherwise defined herein.

      2.    The New Lease is amended so that 6,424 square feet of Net Rentable
Area located on Level 8 (the "Level 8 Space") of the Building and whose location
is shown on Exhibit "A", the Level 8 Space shall be part of the Leased Premises
described in the New Lease. As Base Rental for the Level 8 Space Tenant shall
pay the same Base Annual Rental on a per square foot basis of Net Rentable Area
in the Level 8 Space (calculated and paid on a monthly basis) as the

<PAGE>

Base Annual Rental set forth on Schedule 2 of the New Lease. All terms and
conditions applicable to the Leased Premises under the New Lease shall be
applicable to the Level 8 Space (including, without limitation, Tenant shall pay
all Additional Rent as defined in the New Lease and Tenant shall be entitled to
the Base Rental Credit set forth in Schedule 3 of the New Lease, in lieu of
Tenant Improvement Allowance); however, the Termination Payment provided for in
Section 1.06(b) of the Lease and set forth in Schedule 8 to the Lease shall be
increased by the amounts for the applicable periods set forth on Schedule 1
attached hereto. (Such increase in the Termination Payment represents recapture
of differential in the Base Rental within the Lease Term, and the recapture of
unamortized leasing commissions previously paid by Landlord attributable to the
Level 8 Space).. Base Annual Rental shall commence on the Level 8 Space on the
earlier to occur of the following dates (the "Level 8 Rent Commencement Date"):
(i) October 1, 2004, or (ii) the date Tenant commences to use of the Level 8
Space for purposes other than construction and refurbishment.

      3.    Tenant has inspected the Level 8 Space and if familiar with the
Level 8 Space and Tenant hereby accepts the Level 8 Space "AS-IS", "WHERE-IS"
and "WITH ALL FAULTS" with Landlord having no obligation to make any renovations
or allowance in lieu thereof. The Level 8 Space shall be available to Tenant to
commence installation of any Tenant improvements and refurbishment upon the
execution of this Amendment and all provisions of the New Lease shall be
applicable to the Level 8 Space upon execution of this Amendment except there
shall be no commencement Base Annual Rental or Additional Rental until the Level
8 Rent Commencement Date.

      4.    Tenant warrants and represents that it has not dealt with any other
broker or intermediary entitled to any compensation in connection with this
Amendment or Tenant's occupancy in the Level 8 Space other than Named Broker (as
defined in the New Lease) which shall be paid a commission by Landlord pursuant
to a separate agreement between Landlord and such broker. Each party agrees to
hold the other party, its partners and representatives harmless from any and all
claims, liabilities, costs and expenses (including reasonable attorneys' fees)
arising from any claim for any commission or other fees by any other broker or
agent acting or purporting to act on behalf of such party other than the Named
Broker.

      Except as amended herein, the New Lease remains unchanged and is in full
force and effect in accordance with the terms and provisions contained therein.

      THIS AMENDMENT IS NOT TO BE CONSTRUED AS BINDING UPON LANDLORD WHETHER
LANDLORD PREPARED OR CAUSED THE SAME TO BE PREPARED AND DELIVERED TO TENANT
UNTIL SUCH TIME AS THE SAME IS EXECUTED BY LANDLORD'S AUTHORIZED REPRESENTATIVE
IN THE SPACE PROVIDED BELOW AND DELIVERED TO TENANT.

                                       2
<PAGE>

      This Amendment of Lease is hereby executed and delivered in multiple
counterparts, each of which shall have the force and effect of an original.

"LANDLORD"

TRANSCO TOWER LIMITED

By: McCue Street Investors, LLC
     a limited liability company
     Its General Partner

     By: ERIC P. BLANCHARD
         ----------------------------
         NAME: Assistant Treasurer/
         Its: Assistant Secretary

     By: /s/ [ILLEGIBLE]
         ----------------------------
         Name: [ILLEGIBLE]
         Its: Senior Vice President

Date Executed: 7/19/04

"TENANT"

TRANSCONTINENTAL GAS PIPE LINE CORPORATION

By: /s/ [ILLIGIBLE]
    ---------------------------------
Name: [ILLEGIBLE]
Title: Senior Vice President

Date Executed: 7/11/04

                                       3
<PAGE>

                                   SCHEDULE 1

                               TERMINATION PAYMENT

<TABLE>
<S>                                                                       <C>
Termination Payment Schedule - Transco Third Amendment
NRA of Lease Premises                                                         6.424  S-F.
Sched 8 (a) (represents $0.50/yr x 4.5 yrs x NRA of lease premises) =     $  14.454
Sched 8 (b) (represents $1.22 (*) x 4.5 yrs x NRA of lease premises) =    $  35,163
Sched 8 (c) (represents the unamortized commission on 3/31/00) =          $  52,326
                                                                          ---------
  Termination payment = (a) + (b) + (c)                                   $ 101,943
                                                                          ---------
</TABLE>

(i)   Calculation Of the Deficit of average Base Rental rate OF the lease Term
        Over the Average Base Rental paid from 10/1/04 through 3/31/00:

<TABLE>
<CAPTION>
                                                                  Annual Rate
                          Annual Rate                                Paid
                          -----------                             -----------
<S>                       <C>           <C>                       <C>
10/1/04-3/31/05             $  6.00     10/1/04-3/31/05            $  6.00
 4/1/05-3/31/00               12.00      4/1/05-3/31/06              12.00
 4/1/06-3/31/08               26.00      4/1/06-3/31/07              13.00
 4/1/07-3/31/10               28.00      4/1/07-3/31/08              13.00
 4/1/10-3/31/12               30.00      4/1/08-3/31/09              14.00
 4/1/12-3/31/14               32.00                                  -----
                            -------
                                        Aggregate Base rate
Aggregate Base                          from Commencement Date
 rate far a 9.5 yrs term    $134.00     through Termination Date     58.00

 Divided by 9.5 years          9.50     Divided by 4.5 years          4.50
                            -------                                -------
Average base rental rate    $ 14.11                                $ 12,89
                            -------                                -------

Deficit rate per s.f.       $  1.22
                            -------
</TABLE>
<PAGE>

COMMISSION-TRANSCO HEALTH SERVICES

                                        TABLE DATA

Total Commission              84,531    Table starts at date: [ILLEGIBLE]
                           ---------    or a payment number : [ILLEGIBLE]
  Annual interest rate:         8.00%
         Term in years:          9.5    CURRENT YEAR:          13,415.99
     Payments per year:           12    INTEREST               (4,065.07)
    Final payments due:    11/1/2004

PERIODIC PAYMENT                        PRINCIPAL              (8,55O.92)

ENTERED PAYMENT                       The table uses the calculated periodic
CALCULATED PAYMENT         81,060.97  payment amount unless you enter a value

CALCULATIONS                          for "Entered payment"
     Use payment of        81,060.97  Beginning balance at payment 1: $34,539.33
1st payment in table: 1               Combine interest prior to
                                                           payment 1:[ILLEGIBLE]

<TABLE>
<CAPTION>
            Payment      Beginning                                 Ending       Cumulative
  NO.        Date        Balance       Interest     Principal     Balance        Interest
------     ---------     ---------     --------     ---------     ---------     ----------
<S>        <C>           <C>           <C>          <C>           <C>           <C>
   1       11/1/2004     84,530.05      563.54        497.43      84,033.41         563.54
   2       12/1/2004     84,033.41      560.22        500.75      83,532.66       1,123.76
   3        1/1/2005     83,532.66      556.60        504.09      83,026.57       1,630.65
   4        2/1/2005     83,025.57      563.52        507.45      82,521.12       2,234.17
   5        3/1/2005     82,521.12      550.14        510.83      82,010.29       2,784.31
   6        4/1/2005     82,010.29      546.74        514.24      81,496.05       3,331.05
   7        5/1/2005     81,496.05      543.31        517.67      80,978.38       3,874.35
   8        6/1/2005     80,978.38      539.86        521.12      80,457.26       4,414.21
   9        7/1/2005     80,457.26      536.30        524.39      79,932.67       4,950.59
   10       8/1/2005     79,932.67      532.33        525.09      79,404.58       5,483.46
   11       9/1/2005     79,404.58      529.36        531.61      78,672.97       6,012.64
   12      10/1/2005     78,872.97      525.82        535.15      78,337.82       6,539.66
   13      11/1/2005     78,337.82      522.25        535.72      77,799.10       7,060.91
   14      12/1/2005     77,799.10      516.66        542.31      77,256.76       7,579.57
   15       1/1/2006     77,256.78      515.05        546.93      76,7lO.86       8,094.62
   16       2/1/2006     76,710.55      511.41        549.57      76,161.29       8,606.02
   17       3/1/2006     76,161.29      507.74        553.23      76,608.06       9,113.76
   18       4/1/2006     75,608.04      504.05        556.92      75,051.14       9,617.02
   19       5/1/2006     75,051.14      500.34        560.63      74,490.50      10,118.16
   20       6/1/2006     74,490.50      496.60        564.37      73,926.13      10,614.76
   21       7/1/2006     73,926.13      492.84        566.13      73,358.00      11,107.60
   22       8/1/2006     73,326.00      489.05        571.92      72,755.06      11,596.66
   23       9/1/2006     72,766.05      485.24        575.73      72,210.35      12,081.90
   24      10/1/2006     72,210.35      481.40        579.57      71,630.77      12,563.30
   25      11/1/2006     71,630.77      477.54        583.44      71,047.34      13.040.84
   26      12/1/2006     71,047.34      473.65        587.32      70,460.01      13,514.49
   27       1/1/2007     70,460.01      469.73        591.24      69,068.77      13,984.22
   28       2/1/2007     69,888.77      465.79        595.18      69,273.59      14,450.01
   29       3/1/2007     69,273.59      461.82        599.15      68,674.44      14,911.84
   30       4/1/2007     68,674.44      457.83        603.14      68,071.30      15,369.67
</TABLE>

                                       5
<PAGE>

<TABLE>
<CAPTION>
        PAYMENT       BEGINNING                         ENDING      CUMULATIVE
NO.      DATE          BALANCE   INTEREST  PRINCIPAL    BALANCE      INTEREST
---   ----------      ---------  --------  ---------  ----------    ----------
<S>   <C>             <C>        <C>       <C>        <C>           <C>
 31     5/1/2007      68,071.30   453.81    607.17     67,464.13    15,823.47
 32     6/1/2007      67,454.13   449.76    611.21     66,052.92    16,273.24
 33     7/1/2007      66,852.92   445.59    615.29     66,237.63    16,718.92
 34     8/1/2007      66,237.63   441.58    619.39     65,618.24    17,160.51
 35     9/1/2007      65,618.24   437.65    623.52     64,554.72    17,597.96
 36    10/1/2007      64,994.72   433.30    627.65     64,367.05    18,031.26

 37    11/1/2007      64,367.05   429.11    631.86     63,735.19    18,460.37
 38    12/1/2007      63,735.19   424.90    636.07     63,099.11    18,885.27
 39     1/1/2008      63,099.11   420.55    640.31     62,458.80    19,305.93
 40     2/1/2008      62,458.80   416.39    644.58     61,814.22    19,722.33
 41     3/1/2008      61,814.22   412.09    648.88     61,165.34    20,134.42
 42     4/1/2008      61,165.34   407.77    653.20     60,512.14    20,542.19
 43     5/1/2008      60,512.14   403.41    657.56     59,854.58    20,943.60
 44     6/1/2008      59,854.55   399.03    661.94     59,192.63    21,344.53
 45     7/1/2008      59,192.63   394.62    666.36     58,526.28    21,739.25
 46     8/1/2008      58,526.25   390.18    570.00     57,855.48    22.129.43
 47     9/1/2008      57,855.48   385.70    575.27     57,180.21    22,515.13
 48    10/1/2008      57,180.21   381.20    679.77     56,500.43    22,896.33

 49    11/1/2008      56,500.43   376.67    684.30     55,016.13    23,273.00
 50    12/1/2008      55,816.13   372.11    686.67     55,127.26    23,645.11
 51     1/1/2009      55,127.26   367.52    693.46     54,433.81    24,012.62
 52     2/1/2009      54,433.81   362.59    698.00     53,735.72    24,375.52
 53     3/1/2009      53,735.72   358.24    702.74     53,032.99    24,733.78
 54   [Illegible]     53,032.99   353.55    707.42    [Illegible]   25,067.31
 55     5/1/2009      52,325.57   346.84    712.14     51,613.43    25,436.14
 56     6/1/2009      51,613.43   344.09    716.88     50,096.55    25,780.23
 57     7/1/2009      50,896.55   339.31    721.66     50,174.86    26,119.34
 58     8/1/2009      50,174.88   334.50    726.47     49,448.41    26,454.04
 59     9/1/2009      49,448.41   329.66    731.32     48,717.09    26,703.78
 60    10/1/2009      48,717.09   324.73    736.19     47,980.80    27,103.48

 61    11/1/2009      47,980.90   319.67    741.10     47,239.80    27,428.36
 62    12/1/2009      47,239.80   314.93    746.04     46,493.75    27,743.29
 63     1/1/2010      46,493.75   309.96    751.02     45,742.74    28,053.24
 64     2/1/2010      45,742.74   304.95    756.02     44,986.72    28,358.20
 65     3/1/2010      44,986.72   299.91    761.06     44,225.65    28,658.11
 66     4/1/2010      44,225.65   294.84    766.14     43,459.52    28,952.94
 67     5/1/2010      43,459.52   289.73    771.24     42,688.27    29,242.67
 68     6/1/2010      42,688.27   284.59    776.39     41,911.09    29,527.26
 69     7/1/2010      41,911.09   279.41    781.56     41,130.33    29,806.68
 70     8/1/2010      41,130.33   274.20    786.77     40,343.56    30,080.88
 71     9/1/2010      40,343.56   268.96    792.02     39,551.54    30,349.83
 72    10/1/2010      39,551.54   263.68    797.30     38,754.24    30,613.51

 73    11/1/2010      38,754.24   258.36    802.61     37,951.63    30,871.87
 74    12/1/2010      37,951.63   253.01    807.96     37,143.67    31,124.80
 75     1/1/2011      37,143.67   247.62    813.35     36,330.32    31,372.51
 76     2/1/2011      36,330.32   242.20    818.77     35,511.55    31,614.71
 77     3/1/2011      35,511.55   236.74    824.23     34,687.32    31,851.45
 78     4/1/2011      34,667.32   231.25    829.73     33,857.59    32,082.70
 79     5/1/2011      33,657.59   225.72    835.26     33,022.33    32,308.42
 80     6/1/2011      33,022.33   220.15    840.62     32,181.51    32,528.57
 81     7/1/2011      32,151.51   214.54    846.43     31,335.08    32,743.11
 82     8/1/2011      31,336.08   208.90    852.07     30,483.01    32,952.01
 83     9/1/2011      30,483.01   203.22    857.75     29,625.25    33,155.23
 84    10/1/2011      29,625.25   197.50    863.47     28,761.78    33,352.73

 85    11/1/2011      28,761.78   191.75    869.23     27,892.55    33,544.48
 86    12/1/2011      27,692.55   185.95    675.02     27,017.53    33,730.43
 87     1/1/2012      27,017.53   180.12    860.86     26,136.67    33,910.55
 88     2/1/2012      26,136.67   174.24    886.73     25,249.94    34,084.79
 89     3/1/2012      25,249.94   168.33    892.64     24,357.30    34,253.12
 90     4/1/2012      24,357.30   162.30    898.59     23,458.71    34,415.51
 91     5/1/2012      23,458.71   156.39    904.58     22,554.13    34,571.90
 92     6/1/2012      22,554.13   150.36    910.61     21,643.51    34,722.26
 93     7/1/2012      21,643.31   144.29    916.60     20,726.83    34,866.55
</TABLE>

                                      6
<PAGE>

<TABLE>
<CAPTION>
        Payment     Beginning                              Ending      Cumilatrve
 No.     Date        Balance     Interest    Principal     Balance      Interest
---    ---------    ---------    --------    ---------    ---------    ----------
<S>    <C>          <C>          <C>         <C>          <C>          <C>
 94     8/1/2012    20,726.83      138.18       922.79    19,504.03     35,004.73
 95     9/1/2012    19,504.03      132.03       926.93    18,875.09     35,136.75
 96    10/1/2012    18,575.09      125.63       935.14    17,939.95     35,262.59
 97    11/1/2012    17,939.95      119.60       941.37    16,998.57     35,382.19
 98    12/1/2012    16,998.57      113.32       947.65    16,050.92     35,495.51
 99     1/1/2013    16,050.92      107.01       953.97    15,096.96     35,602.52
100     2/1/2013    15,096.95      100.65       960.33    14,136.63     35,703.16
101     3/1/2013    14,136.63       94.24       966.73    13,169.90     35,797.41
102     4/1/2013    13,169.90       87.80       973.17    12,196.72     35,885.21
103     5/1/2013    12,196.72       81.31       979.66    11,217.06     35,966.52
104     6/1/2013    11,217.06       74.78       966.19    10,230.87     36,041.30
105     7/1/2013    10,230.87       68.21       992.77     9,238.10     36,109.31
106     8/1/2013     9,238.10       61.59       999.39     8,238.71     36,171.09
107     9/1/2013     5,235.71       54.92     1,006.05     7,232.66     36,226.02
108    10/1/2013     7,232.66       48.22     1,012.76     5,219.91     36,274.24
109    11/1/2013     6,219.91       41.47     1,019.51     5,200.40     36,315.70
110    12/1/2013     5,200.40       34.67     1,026.30     4,174.10     36,350.37
111     1/1/2014     4,174.10       27.83     1,033.15     3,140.95     36,378.20
112     2/1/2014     3,140.95       20.94     1,040.03     7,100.92     36,399.14
113     3/1/2014     2,100.92       14.01     1,046.97     1,053.95     36,413.14
114     4/1/2014     1,053.95        7.03     1,053.95         0.00     36,420.17
</TABLE>

                                        7
<PAGE>

                                  EXHIBIT "A"

                                  [FLOOR PLAN]

                                    LEVEL 8

                                 WILLIAMS TOWER
<PAGE>

                     EXTENSION OF SECOND AMENDMENT OF LEASE
                      BY AND BETWEEN TRANSCO TOWER LIMITED
                 AND TRANSCONTINENTAL GAS PIPE LINE CORPORATION

      This Extension of Second Amendment of Lease (the "Extension") is for
reference purposes dated as of June 25, 2004, but executed as of the dates set
forth below the parties' signatures, and is made and entered by and between
TRANSCO TOWER LIMITED ("Landlord") and TRANSCONTINENTAL GAS PIPE LINE
CORPORATION ("Tenant").

                                   WITNESSETH:

      WHEREAS, the following facts currently exist:

      A. A certain Lease Agreement (the "Original New Lease") was made and
entered into on October 23, 2003 by and between Landlord and Tenant, under the
terms of which Landlord leased to Tenant certain demised premises in the
building known as the Williams Tower located at 2800 Post Oak Boulevard,
Houston, Harris County, Texas (the "Building"). The Original New Lease was
amended by (i) First Amendment of Lease ("First Amendment") dated for reference
purposes as of March 10, 2004, to incorporate space on Level 5 of the Building
into the Original New Lease, and (ii) Second Amendment of Lease ("Second
Amendment") dated for reference purposes as of March 11, 2004, to incorporate
space on Level 36 of the Building into Original New Lease. The Original New
Lease, as amended by the First Amendment and Second Amendment, is herein called
the "New Lease".

      B. Tenant currently, pursuant to the New Lease, leases premises in the
Building including 23,090 square feet of Net Rentable Area (as defined in the
New Lease) located on Level 36 of the Building (the location of which space is
particularly shown on Exhibit A attached to the Second Amendment and made a part
thereof and hereof and is herein called the "Level 36 Space"). The Level 36
Space is occupied by an affiliate of Tenant, Williams Field Services Company
("Services").

      C. The New Lease expires as to the Level 36 Space on June 27, 2004, and
upon such expiration, Tenant's right to lease and occupy, and Services occupancy
of, the Level 36 Space will terminate.

      D. Tenant has requested that Tenant be allowed to continue to lease, and
for Tenant or Services to occupy, the Level 36 Space after the expiration of the
New Lease as to the Level 36 Space through September 30, 2004. Landlord is
agreeable to so extending the New Lease as to the Level 36 Space under the terms
and conditions herein set forth.

      NOW THEREFORE, in consideration of Ten Dollars ($10.00) paid by Tenant to
Landlord, and other good and valuable consideration by each of the parties
hereto to the other, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

<PAGE>

      1. The above recitals are hereby incorporated herein for all purposes, and
all terms used herein shall have the same meanings as in the New Lease, except
as otherwise defined herein.

      2. Upon the current expiration of the New Lease as to the Level 36 Space,
Tenant or Services may continue to occupy the Level 36 Space through September
30, 2004 (the "Extended Expiration Date"), with each of Landlord and Tenant
having the right to terminate the New Lease as to the Level 36 Space sooner than
the Extended Expiration Date, upon 30 days' prior written notice to the other.

      3. Services, by executing this Extension, is evidencing Services'
agreement to the provisions hereof and its agreement to vacate the Level 36
Space on or before the Extended Expiration Date, or the earlier termination of
the New Lease as to the Level 36 Space, however the same may be brought about.

      4. Tenant warrants and represents that it has not dealt with any other
broker or intermediary entitled to any compensation in connection with this
Extension other than Named Broker (as defined in the New Lease) which shall be
paid a commission by Landlord pursuant to a separate agreement between Landlord
and such broker. Each party agrees to hold the other party, its partners and
representatives harmless from any and all claims, liabilities, costs and
expenses (including reasonable attorneys' fees) arising from any claim for any
commission or other fees by any other broker or agent acting or purporting to
act on behalf of such party other than Named Broker.

      Except as amended by the terms of this Extension, the New Lease including,
but not limited to, the Second Amendment thereto, remains unchanged and is in
full force and effect in accordance with the terms and provisions contained
therein.

      THIS EXTENSION IS NOT TO BE CONSTRUED AS BINDING UPON LANDLORD WHETHER
LANDLORD PREPARED OR CAUSED THE SAME TO BE PREPARED AND DELIVERED TO TENANT
UNTIL SUCH TIME AS THE SAME IS EXECUTED BY LANDLORD'S AUTHORIZED REPRESENTATIVE
IN THE SPACE PROVIDED BELOW AND DELIVERED TO TENANT.

                                       2
<PAGE>

      This Extension is hereby executed and delivered in multiple counterparts,
each of which shall have the force and effect of an original.

"LANDLORD"

TRANSCO TOWER LIMITED

By:     McCue Street Investors, LLC
        a limited liability company
        Its General Partner

        By:  /s/ Eric P. Blanchard
             ---------------------------------------
            Name:       Eric P. Blanchard
            Its:        Assistant Treasurer
                        Assistant Secretary

        By:  /s/ Louis E. Herrera, Jr.
             ---------------------------------------
            Name:       Louis E. Herrera. Jr.
            Its:        Assistant Secretary

Date Executed: 6/30/04

"TENANT"

TRANSCONTINENTAL GAS PIPE LINE CORPORATION

By:   /s/       [ILLEGIBLE]
      -------------------------------------
    Name:       [ILLEGIBLE]

    Title:      VICE PRESIDENT

Date Executed: June 25, 2004

                                       3
<PAGE>

AGREED AND ACCEPTED BY WILLIAMS
FIELD SERVICES COMPANY, this______day of
_______________2004:

WILLIAMS FIELD SERVICES COMPANY

By: /s/ Alan S. Armstrong
    --------------------------------
     NAME:  Alan S. Armstrong
     TITLE: Senior Vice President

                                       4<PAGE>

                                                                    EXHIBIT 10.1

SILICON VALLEY BANK

                               AMENDMENT AGREEMENT

BORROWER:   ATS MEDICAL SALES, INC.
            ATS MEDICAL, INC.

DATE:       MARCH 24, 2005

         THIS AMENDMENT AGREEMENT ("Amendment") is entered into between Silicon
Valley Bank ("Silicon") and the borrower named above ("Borrower"), with
reference to the following facts:

         A. Silicon and Borrower are parties to that certain Loan and Security
Agreement, with an Effective Date of July 28, 2004 (as amended, the "Loan
Agreement"). (The Loan Agreement and all other present and future documents,
instruments and agreements relating thereto are referred to herein collectively
as the "Loan Documents". Capitalized terms used in this Agreement which are not
defined herein shall have the meanings set forth in the Loan Agreement.)

         B. The parties desire to amend the Loan Agreement, as set forth in this
Amendment.

         The parties agree as follows:

         1.  FINANCIAL COVENANTS.  Section 6.7 of the Loan Agreement reads as
             follows:

             Borrower will maintain at all times, on a consolidated basis:

             (i) LIQUIDITY RATIO. A ratio of (y) unrestricted cash (and
             equivalents) of Borrower on deposit with Bank plus Borrower's
             Eligible Accounts, (z) divided by Current Liabilities, of
             equal to or greater than 2.25 to 1.00.

             (ii) TANGIBLE NET WORTH. A Tangible Net Worth of at least the
             following amounts for the following periods:

             The Closing Date through September 30, 2004             $52,000,000
             October 1, 2004 through December 31, 2004               $49,000,000
             January 1, 2005 through March 31, 2005                  $46,000,000
             April 1, 2005 through June 30, 2005                     $44,000,000
             July 1, 2005 and thereafter                             $42,000,000

<PAGE>

         Section 6.7 of the Loan Agreement is hereby amended to read as follows,
effective as of April 1, 2005:

             Borrower will maintain at all times, on a consolidated basis:

             (i) LIQUIDITY RATIO. A ratio of (y) unrestricted cash (and
             equivalents) of Borrower on deposit with Bank plus Borrower's
             Eligible Accounts, (z) divided by Current Liabilities, of
             equal to or greater than 2.00 to 1.00.

             (ii) TANGIBLE NET WORTH.  A Tangible Net Worth of at least the
             following amounts for the following periods:

             The Closing Date through September 30, 2004             $52,000,000
             October 1, 2004 through December 31, 2004               $49,000,000
             January 1, 2005 through March 31, 2005                  $42,000,000
             April 1, 2005 through June 30, 2005                     $39,000,000
             July 1, 2005 and thereafter                             $36,000,000

         2. AMENDMENT FEE. In consideration for Silicon entering into this
Agreement, Borrower shall concurrently pay Silicon a fee in the amount of
$1,000, which shall be non-refundable and in addition to all interest and other
fees payable to Silicon under the Loan Documents. Silicon is authorized to
charge said fee to Borrower's loan account.

         3. REPRESENTATIONS TRUE. Borrower represents and warrants to Silicon
that all representations and warranties set forth in the Loan Agreement, as
amended hereby, are true and correct.

         4. GENERAL PROVISIONS. This Amendment, the Loan Agreement, any prior
written amendments to the Loan Agreement signed by Silicon and Borrower, and the
other Loan Documents set forth in full all of the representations and agreements
of the parties with respect to the subject matter hereof and supersede all prior
discussions, representations, agreements and under-standings between the parties
with respect to the subject hereof. Except as herein expressly amended, all of
the terms and provisions of the Loan Agreement, and all other Loan Documents
shall continue in full force and effect and the same are hereby ratified and
confirmed. This Amendment is part of the Loan Agreement and its terms are
incorporated herein.

<PAGE>

BORROWER:                                        SILICON:

ATS MEDICAL SALES, INC.                          SILICON VALLEY BANK

By:  /s/ John R. Judd                            By:  /s/ Charles Roehl
Name:  John R. Judd                              Title:  VP Relationship Manager
Title:  Chief Financial Officer

ATS MEDICAL, INC.

By:  /s/ John R. Judd
Name:  John R. Judd
Title:  Chief Financial Officer

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00081-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00081-of-00352.parquet"}]]