<PAGE>

                                                                   Exhibit 10.27
                                 Office Lease

                                      For

                               3333 Finley Road
                            Downers Grove, Illinois


                                    Between

                           BANK ONE, ILLINOIS, N.A.,

                       as Trustee under Trust No. 11097,

                                   Landlord,

                                      and

                               MAY & SPEH, INC.,
                            a Delaware corporation

                                    Tenant

                              Dated: June 2, 1997


<PAGE>
 
                               TABLE OF CONTENTS

                                                                            PAGE
                                                                            ----

SCHEDULE OF SIGNIFICANT TERMS.............................................   -1-
 
SUPPLEMENTAL PROVISIONS...................................................   -3-
    S.1       Definitions.................................................   -3-
    S.2       Option to Extend............................................   -3-
    S.3       Vacant Space................................................   -4-
    S.4       Tenant's Option To Purchase.................................   -5-
    S.5       Development of Third Building Parcel........................   -6-
    S.6       Net Lease...................................................   -6-
    S.7       Right of First Offer........................................   -6-

ARTICLE 1.    GRANT AND TERM..............................................  -10-
    1.01      Grant of Lease..............................................  -10-
    1.02      Possession..................................................  -10-
    1.03      Lease Year..................................................  -10-

ARTICLE 2.    CONSTRUCTION OF IMPROVEMENTS................................  -10-
    2.01      Construction of Improvements................................  -10-
    2.02      Landlord's Obligations......................................  -11-
    2.03      Contractor and Architect....................................  -11-
    2.04      Landlord's Right to Make Changes............................  -11-
    2.05      Definition of Changes.......................................  -12-
    2.06      Costs of Changes............................................  -12-
    2.07      Substitution of Materials...................................  -12-
    2.08      Definition of Costs.........................................  -12-
    2.09      Payment of Costs............................................  -13-
    2.10      Tenant's Right to Inspect the Building......................  -13-
    2.11      Completion Date for the Building............................  -13-
    2.12      Definition of Ready for Occupancy...........................  -14-
    2.13      Punch List..................................................  -14-
    2.14      Contractor's and Landlord's Warranty........................  -15-
    2.15      Compliance with Law.........................................  -15-
    2.16      Definition of Delays........................................  -15-
    2.17      Obligations of the Architects...............................  -16-
    2.18      Limitation of Landlord's Construction Obligation............  -16-

ARTICLE 3.    BASE RENT...................................................  -17-
    3.01      Base Rent...................................................  -17-
    3.02      Manner of Payment...........................................  -17-
 
                                      i 
<PAGE>
 
ARTICLE 4.    TAXES                                                         -17-
    4.01      Obligation to Pay Tax Rent Adjustments                        -17-
    4.02      Definitions                                                   -17-
    4.03      Payments of Tax Rent Adjustments                              -18-
    4.04      Proration and Survival                                        -19-
 
ARTICLE 5.    USE OF PREMISES                                               -19-
                                                                            
ARTICLE 6.    UTILITIES                                                     -19-
    6.01      Payment for Utilities                                         -19-
    6.02      Utilities                                                     -20-
                                                                            
ARTICLE 7.    CONDITION, CARE AND OPERATION OF PREMISES                     -20-
    7.01      Condition of Premises                                         -20-
    7.02      Tenant's Maintenance and Operation Obligations                -20-
    7.03      Work Performed by Tenant                                      -21-
    7.04      Janitorial Service                                            -21-
    7.05      Waste                                                         -21-
                                                                            
ARTICLE 8.    RETURN OF PREMISES                                            -21-
    8.01      Surrender of Possession                                       -21-
    8.02      Installations and Additions                                   -22-
    8.03      Trade Fixtures and Personal Property                          -22-
    8.04      Survival                                                      -22-
                                                                            
ARTICLE 9.    HOLDING OVER                                                  -22-
                                                                            
ARTICLE 10.   RULES AND REGULATIONS                                         -23-
                                                                            
ARTICLE 11.   RIGHTS RESERVED TO LANDLORD                                   -23-
    11.01     Rights Reserved to Landlord                                   -23-
                                                                            
ARTICLE 12.   ALTERATIONS                                                   -24-
                                                                            
ARTICLE 13.   ASSIGNMENT AND SUBLETTING                                     -25-
    13.01     Assignment and Subletting                                     -25-
    13.02     Rentals Based on Net Income                                   -25-
    13.03     Tenant to Remain Obligated                                    -25-
    13.04     Landlord's Consent                                            -25-
    13.05     Profits                                                       -26-
    13.06     Assignee to Assume Obligations                                -27-
    13.07     Change of Control                                             -27-
    13.08     Transfer By Merger or Sale or To an Affiliate                 -27-
    13.09     Sublease with Customers                                       -29-
    13.10     Restrictions on Assignment and Sublease.                      -29-
 


                                    ii    
<PAGE>
 
ARTICLE 14.   WAIVER OF CERTAIN CLAIMS; INDEMNITY BY TENANT...............  -29-
    14.01     Waiver of Certain Claims; Indemnity by Tenant...............  -29-
    14.02     Damage Caused by Tenant's Neglect...........................  -29-
    14.03     Tenant Responsible for Personal Property....................  -30-
    14.04     Indemnification.............................................  -30-

ARTICLE 15.   DAMAGE OR DESTRUCTION BY CASUALTY...........................  -30-
    15.01     Tenant's Obligation to Rebuild..............................  -30-
    15.02     Preconditions to Rebuilding.................................  -30-
    15.03     Payment for Rebuilding......................................  -31-
    15.04     Excess Insurance Proceeds...................................  -31-
    15.05     Failure to Rebuild..........................................  -31-
    15.06     Deposits....................................................  -31-

ARTICLE 16.   EMINENT DOMAIN..............................................  -32-
    16.01     Whole Taking................................................  -32-
    16.02     Partial Taking..............................................  -33-

ARTICLE 17.   DEFAULT.....................................................  -33-
    17.01     Events of Default...........................................  -33-
    17.02     Rights and Remedies of Landlord.............................  -34-
    17.03     Right to Re-Enter...........................................  -35-
    17.04     Current Damages.............................................  -35-
    17.05     Final Damages...............................................  -35-
    17.06     Removal of Personal Property................................  -36-
    17.07     Attorneys' Fees.............................................  -36-
    17.08     Assumption or Rejection in Bankruptcy.......................  -36-

ARTICLE 18.   SUBORDINATION...............................................  -37-
    18.01     Subordination...............................................  -37-
    18.02     Liability of Holder of First Mortgage; Attornment...........  -37-
    18.03     Modification Required by First Mortgagee....................  -37-
    18.04     Short Form Lease............................................  -38-

ARTICLE 19.   MORTGAGEE PROTECTION........................................  -38-

ARTICLE 20.   ESTOPPEL CERTIFICATE........................................  -38-

ARTICLE 21.   SUBROGATION AND INSURANCE...................................  -39-
    21.01     Waiver of Subrogation.......................................  -39-
    21.02     Tenant's Insurance..........................................  -39-
    21.03     Certificates of Insurance...................................  -40-
    21.04     Compliance with Requirements................................  -41-

ARTICLE 22.   NONWAIVER...................................................  -41-

ARTICLE 23.   TENANT'S AUTHORITY..........................................  -41-


                                      iii
<PAGE>
 
ARTICLE 24.   REAL ESTATE BROKERS.........................................  -42-

ARTICLE 25.   NOTICES.....................................................  -42-

ARTICLE 26.   HAZARDOUS MATERIALS.........................................  -42-
    26.01     Defined Terms...............................................  -42-
    26.02     Tenant's Obligations with Respect to Environmental Matters..  -43-
    26.03     Copies of Notices...........................................  -44-
    26.04     Landlord's Right to Inspect.................................  -44-
    26.05     Tests and Reports...........................................  -44-
    26.06     Tenant's Obligation to Respond..............................  -45-
    26.07     Landlord's Right to Act.....................................  -45-
    26.08     Indemnification.............................................  -45-

ARTICLE 27.   TITLE AND COVENANT AGAINST LIENS............................  -46-

ARTICLE 28.   MISCELLANEOUS...............................................  -46-
    28.01     Successors and Assigns......................................  -46-
    28.02     Modifications in Writing....................................  -47-
    28.03     No Option; Irrevocable Offer................................  -47-
    28.04     Financial Statements........................................  -47-
    28.05     Definition of Landlord......................................  -47-
    28.06     Headings....................................................  -47-
    28.07     Time of Essence.............................................  -47-
    28.08     Default Rate of Interest....................................  -47-
    28.09     Severability................................................  -47-
    28.10     Entire Agreement............................................  -48-

ARTICLE 29.   EXCULPATORY PROVISIONS                                        -48-

Attachments:  EXHIBIT A   THE LAND
              EXHIBIT B   FORM OF COMMENCEMENT NOTICE
              EXHIBIT C   OUTLINE SPECIFICATIONS FOR BASE BUILDING IMPROVEMENTS
              EXHIBIT D   SCHEDULE OF PLAN SUBMISSIONS
              EXHIBIT E   DIVISION OF RESPONSIBILITY BETWEEN BASE BUILDING
                          IMPROVEMENTS AND OFFICE IMPROVEMENTS
              EXHIBIT F   APPROVED CONTRACTORS
              EXHIBIT G   REQUIRED COMPLETION DATES
              RIDER A     BASE RENT
              RIDER B     RULES AND REGULATIONS
              RIDER C     CLEANING SPECIFICATIONS
              RIDER D     INITIAL ESTOPPEL CERTIFICATE
              RIDER E     PURCHASE CONTRACT
              RIDER F     OPERATION AND MAINTENANCE STANDARDS

                                      iv
<PAGE>
 
        LEASE with MAY & SPEH, INC., a Delaware corporation ("Tenant")

                        on Premises at 3333 Finley Road
                        Downers Grove, Illinois  60515


    This Lease made as of the Date of Lease set forth in the following Schedule
(the "Schedule"), by and between Bank One, Illinois, N.A., not personally but
solely as Trustee under Trust Agreement dated May 23, 1997, and known as Trust
No. 11097 ("Landlord") and the Tenant identified immediately above.


                         SCHEDULE OF SIGNIFICANT TERMS

     For purposes of this Lease, the terms set forth below shall have the
meanings or be assigned the amounts as follows:

Date of Lease:                      June 2, 1997

Base Rent (annual amount):          See attached Rider A

Monthly Base Rent:                  One Twelfth of annual Base Rent

Commencement Date:                  The later of (i) September 1, 1998 and (ii)
                                    the last Phase Commencement Date

Expiration Date:                    The last day of the 20th Lease Year (as
                                    defined herein) or such earlier date as this
                                    Lease is terminated as provided herein;
                                    provided that if the Term of this Lease is
                                    extended for an Extended Term, the
                                    Expiration Date shall be the last day of
                                    such Extended Term.

Term:                               The period beginning on the first Phase
                                    Commencement Date and ending on the
                                    Expiration Date.

Land:                               That certain parcel of real estate legally
                                    described on Exhibit A attached hereto and
                                    made a part hereof.

Building:                           The improvements to be constructed on the
                                    land which is to be commonly known as 3333
                                    Finley Road, Downers Grove, Illinois 60515,
                                    consisting of an eight (8) story office
                                    building, in accordance with Article 2
                                    herein.

<PAGE>
 
Premises:                           The entire Building and Land.

Tenant's Address for Notices:       At the Premises.

Tenant's Authorized
Representative:                     Eric Loughmiller

Attachments to Lease:               Exhibit A  The Land
                                    Exhibit B  Form of Commencement Notice
                                    Exhibit C  Outline Specifications for Base
                                               Building Improvements
                                    Exhibit D  Schedule of Plan Submissions
                                    Exhibit E  Division of Responsibility
                                               Between Base Building
                                               Improvements and Office
                                               Improvements
                                    Exhibit F  Approved Contractors
                                    Exhibit G  Required Completion Dates
                                    Rider A    Base Rent
                                    Rider B    Rules and Regulations
                                    Rider C    Cleaning Specifications
                                    Rider D    Initial Estoppel Certificate
                                    Rider E    Purchase Contract
                                    Rider F    Operation and Maintenance 
                                               Standards

                                      -2-
<PAGE>
 
                            SUPPLEMENTAL PROVISIONS

S.1   Definitions.  As used herein,

     (a)  "1501 Lease" means the lease dated as of the Date of this Lease
between Landlord and Tenant for the building located at 1501 Opus Place, Downers
Grove, Illinois and the land thereunder.

     (b)  "Purchase and Sale Agreement" means the agreement dated April 16, 1997
under which Landlord purchased the Land and the premises under the 1501 Lease
from Tenant.

     (c)  "Phase Commencement Date" means with respect to each Office Space
Phase defined in Exhibit G, the later of (i) September 1, 1998 and (ii) the date
forty-five (45) days after the Ready for Occupancy date (as defined herein) for
such Office Space Phase.

S.2  Option to Extend.

     (a)  If (i) Tenant is not then in Default hereunder, and (ii) Tenant has
simultaneously exercised its option to extend the term of the 1501 Lease, then
Tenant shall have the option to extend the Term for an additional five (5) year
period commencing on the day next following the Expiration Date and ending on
the fifth (5th) anniversary of the Expiration Date ("First Extended Term") by
giving written notice of said extension to Landlord not later than nine (9)
months prior to the Expiration Date, time being of the essence.

     (b)  If (i) Tenant is not then in Default hereunder, and (ii) Tenant has
previously exercised its option to extend the Term for the First Extended Term
and has simultaneously exercised its option to extend the term of the 1501 Lease
for a like period, then Tenant shall have the option to extend the Term for an
additional five (5) year period commencing on the day next following the fifth
(5th) anniversary of the Expiration Date and ending on the tenth (10th)
anniversary of the Expiration Date ("Second Extended Term") by giving written
notice of said extension to Landlord not later than nine (9) months prior to the
end of the First Extended Term, time being of the essence.

     (c)  If (i) Tenant is not then in Default hereunder, and (ii) Tenant has
previously exercised its option to extend the Term for the Second Extended Term
and has simultaneously exercised its option to extend the term of the 1501 Lease
for a like period, then Tenant shall have the option to extend the Term for an
additional five (5) year period commencing on the day next following the tenth
(10th) anniversary of the Expiration Date and ending on the fifteenth (15th)
anniversary of the Expiration Date ("Third Extended Term") by giving written
notice of said extension to Landlord not later than nine (9) months prior to the
end of the Second Extended Term, time being of the essence. The First Extended
Term, Second Extended Term and Third Extended Term are hereinafter individually
and collectively referred to as the "Extended Term".

                                      -3-
<PAGE>
 
     (d)  If the Term is extended it shall be so extended on the same terms and
conditions then set forth in this Lease, including the annual Base Rent as set
forth in Rider A.

     (e)  Landlord and Tenant shall enter into a written supplement to this
Lease confirming the terms, conditions and provisions applicable during the
Extended Term as determined in accordance with the provisions of this Section
S.2. If Tenant fails to timely exercise its option to extend the Term for the
applicable Extended Term, then this Lease shall expire by its terms on the
expiration of the Term or the First Extended Term or the Second Extended Term,
as the case may be.

S.3  Vacant Space

     (a)  Landlord and Tenant acknowledge that even though the Premises includes
the entire Building, Tenant does not intend to initially occupy the second and
third floors ("Vacant Space") of the Building and the Office Improvements will
not include any construction on such floors. Additionally, prior to September 1,
2000, the annual Base Rent will not include any amount for the Vacant Space
unless Tenant occupies a portion of such floors for the conduct of its business.
Tenant shall notify Landlord in writing at least thirty (30) days prior to the
date Tenant intends to occupy any portion of the Vacant Space for the conduct of
its business (which shall not include use of such space for storage).

     (b)  All alterations, additions, improvements or modifications required for
Tenant's initial use of the Vacant Space ("Vacant Space Alterations") shall be
made by Tenant, at its sole cost and expense, except as provided below, in
accordance with the provisions of this Lease including without limitation
Article 12. Notwithstanding the foregoing, Landlord shall provide Tenant with an
allowance ("Vacant Space Construction Allowance") of $1,250,000 to be applied to
the cost of the Vacant Space Alterations incurred by Tenant from time to time,
including without limitation, the cost to prepare the plans and specifications
for such work. When and as Tenant occupies portions of the Vacant Space for the
conduct of its business, Landlord shall pay a portion of the Vacant Space
Construction Allowance to Tenant. The portion payable to Tenant upon such
occupancy shall be the lesser of (i) the cost of the Vacant Space Alterations
for the portion of the space occupied by Tenant and (ii) $1,250,000 multiplied
by the decimal equivalent of the percentage of the Vacant Space occupied by
Tenant. Landlord shall pay such portion of the Vacant Space Construction
Allowance to Tenant in accordance with paragraph (c) below.

     (c)  Tenant may draw funds against the Vacant Space Construction Allowance
at any time and from time to time subject to the following:

          (i)    Tenant may not make more than one draw in any calendar month;

                                      -4-
<PAGE>
 
          (ii)   Except for the final draw, the maximum amount of any draw shall
     not exceed an amount which bears the same ratio to the portion of the
     Vacant Space Construction Allowance applicable to the space being improved
     by Tenant as the cost of the Vacant Space Alterations for such space paid
     by Tenant and covered by the lien waivers submitted by Tenant in connection
     with the draw request bears to the total cost of the Vacant Space
     Alterations for such space;

          (iii)  With each draw request Tenant shall submit to Landlord the
     following documents:

                 (A)  A true and correct copy of the application for payment by
          Tenant's contractors for Vacant Space Alterations for the space in
          question completed to date, including contractor's affidavits and
          sworn statements evidencing cost of Vacant Space Alterations for the
          space in question performed to date;

                 (B)  Partial or final lien waivers with respect to Vacant Space
          Alterations for the space in question performed to date;

                 (C)  Tenant's certification to Landlord that the amounts set
          forth in all Contractor's sworn statements are owed to Tenant's
          contractors for Vacant Space Alterations for the space in question
          performed to date;

                 (D)  The total cost of Vacant Space Alterations for the space
          in question based on the plans approved by Landlord, as such cost may
          change from time to time;

                 (E)  With the final draw request, Tenant shall submit to
          Landlord a certificate from Tenant's architect stating that Vacant
          Space Alterations for the space in question has been completed in
          accordance with the Plans approved by Landlord and applicable zoning,
          building, environmental and other laws.

          (iv)   Landlord will disburse the portion of the Vacant Space
     Construction Allowance allocable to each draw request to Tenant or Tenant's
     contractors (at Tenant's option) within thirty (30) days after Tenant has
     submitted the required information for such draw and has otherwise complied
     with the requirements hereof.

S.4 Tenant's Option To Purchase.  If Tenant exercises its option under the 1501
Lease to purchase the premises under such lease on the Closing Date defined
below, then Tenant shall have the option to purchase the Premises on September
1, 2001 or September 1, 2006 (the applicable date chosen by Tenant herein called
the "Closing Date") on the terms and conditions set forth in the Purchase
Contract attached hereto as Rider E ("Purchase Contract"). Tenant shall exercise
such option by delivery of written notice to Landlord on or before the February


                                      -5-
<PAGE>
 
1 preceding the Closing Date exercising such option and four copies of the
Purchase Contract, with the Purchase Price and Closing Date filled in, executed
by Tenant. Time is of the essence in the exercise of the option to purchase set
forth in this Section S.4. If Tenant exercises the option as set forth in this
Section, Landlord shall execute the Purchase Contract and deliver two executed
copies thereof to Tenant. The Premises shall be purchased on the terms and
conditions set forth in the Purchase Contract.

     S.5  Development of Third Building Parcel.  Landlord shall have the right
to construct a building on the portion of the Land designated as the Third
Building Parcel on attached Exhibit A provided, that (i) Landlord replaces the
surface parking spaces on such parcel used in connection with the Building with
other surface parking spaces ("Replacement Spaces") on or adjacent to the Land
or in a parking structure constructed by Landlord on or adjacent to the Third
Building Parcel and (ii) Landlord obtains Tenant's consent to any development of
the Third Building Parcel commencing prior to September 1, 2007. Upon the
commencement of any development by Landlord of the Third Building Parcel, the
Third Building Parcel shall be deleted from the Premises and Land for purposes
of this Lease, and Landlord shall provide Tenant with appropriate easements for
access to and use of any Replacement Spaces not located on the Land. If Tenant
consents to the development of the Third Building Parcel prior to September 1,
2007, then Tenant's option to purchase the Premises under Section S.4 above
shall not include the Third Building Parcel.

     S.6  Net Lease.  This is an absolutely net lease to Landlord. It is the
intent of the parties hereto that the Base Rent payable under this Lease shall
be an absolutely net return to the Landlord and that the Tenant shall pay all
costs and expenses relating to the Premises and the business carried on therein,
unless otherwise expressly provided in the Lease. Any amount or obligation
relating to the Premises which is not expressly declared to be that of Landlord
shall be deemed to be an obligation of the Tenant to be performed by the Tenant
at the Tenant's expense.

     S.7  Right of First Offer.

          (a)  Landlord hereby grants to Tenant, the right of first offer on any
     disposition of the Premises excepting those dispositions specified in
     Section S.7(b) below and subject to Section S.7(c) below.

          (b)  This right of first offer shall not apply to the following
     dispositions of the Premises:

               (i)    any dispositions to any person or party who may acquire an
          interest in the Premises in the nature of a security interest for a
          bona fide obligation of any party owning an interest in the Premises
          or any transferee thereof, whether by way of pledge, collateral
          agreement, or mortgage,

                                      -6-
<PAGE>
 
               (ii)   any person or party who may acquire an interest in the
          Premises as a result of the enforcement (or transfer in lieu of
          enforcement) of any bona fide obligation secured by an interest in the
          Premises, or any transferee thereof, whether by way of purchase at any
          Sheriff, judicial, or other sale, termination of lease and eviction of
          the lessee thereunder, or any other remedy to which the holder of said
          obligation is entitled,

               (iii)  any disposition to a Landlord Affiliate,

               (iv)   a leasehold interest in space in the Building, or

               (v)    any disposition after September 1, 2006.

          (c)  If Landlord shall desire to dispose of (any type of disposition
     is hereinafter called "sale") the Premises in a transaction not excepted by
     Section S.7(b), Landlord shall give Tenant written notice to that effect
     which notice shall specify the price and financial terms ("Landlord's Price
     and Terms") on which Landlord is willing to sell the Premises. Tenant shall
     have the right at anytime during the thirty (30) day period following the
     giving of such notice to give Landlord notice:

               (i)    that Tenant will purchase the Premises at Landlord's Price
          and Terms, in which event the closing of said purchase shall occur on
          a date selected by Tenant which date shall be between sixty (60) and
          ninety (90) days after Tenant gives such notice;

               (ii)   of the price and financial terms ("Tenant's Price and
          terms") on which Tenant is willing to purchase the Premises and the
          proposed closing date for said purchase which shall be between sixty
          (60) and ninety (90) days after the giving of such notice, or

               (iii)  that Tenant waives its right of first offer to purchase
          the Premises.

          (d)  If Tenant gives the notice stated in Section S.7(c)(ii) then
     Landlord by written notice to Tenant within thirty (30) days after receipt
     of Tenant's Notice, shall elect either:

               (i)    to sell the Premises at Tenant's Price and Terms, in which
          event the closing of such sale shall occur on the closing date set
          forth in Tenant's notice, or

               (ii)   not to sell the Premises to Tenant at Tenant's Price and
          Terms.

          If Landlord fails to give Tenant any such notice within said thirty
     (30) day period, Landlord shall be deemed to have given the notice
     specified in (ii) immediately above.

                                      -7-
<PAGE>
 
          (e)  (i)  If Landlord gives or is deemed to have given the notice
          specified in Section S.7(c)(ii), Landlord may enter into a written
          agreement to sell the Premises at any time during the one hundred
          eighty (180) day period after receipt of Tenant's notice for a price
          and terms equal to or greater than (but not less than) Tenant's Price
          and Terms. If Landlord does not enter into said written agreement
          within said one hundred eighty (180) day period, or, if said agreement
          is entered into, Landlord does not close the sale within two hundred
          seventy (270) days after receipt of Tenant's notice, at a price and
          terms equal to or greater than Tenant's Price and terms, then Landlord
          may not sell the Premises without again giving Tenant notice of its
          desire to sell the Premises as required by Section S.7(c).

               (ii)   If Tenant gave or is deemed to have given the notice in
          Section S.7(c)(iii) then Landlord may enter into a written agreement
          to sell the Premises at any time during the one hundred eighty (180)
          day period after receipt of Tenant's notice or if no notice is given
          within two hundred forty (240) days after Landlord's Notice on any
          terms and conditions. If Landlord does not enter into said written
          agreement within said one hundred eighty (180) or two hundred forty
          (240) day period, or, if said agreement is entered into, Landlord does
          not close the sale within two hundred seventy (270) days after receipt
          of Tenant's notice or three hundred thirty (330) days after Landlord's
          Notice, as the case may be, then Landlord may not sell the Premises
          without again giving Tenant notice of its desire to sell said interest
          in the Premises as required by Section S.7(c).

          (f)  If Tenant does not purchase the Premises offered pursuant to this
     Section S.7 and the Premises is sold by Landlord in accordance with this
     Section S.7, then Tenant shall have no further right of first offer under
     this Section S.7 to purchase the Premises, but nothing herein shall affect
     Tenant's option to purchase the Premises pursuant to Section S.4 above.

          (g)  At such time as the rights of first offer of Tenant hereunder
     shall cease and be at an end and null and void, then at Landlord's request
     Tenant shall execute and deliver to Landlord an instrument in recordable
     form releasing all of its right under this Section S.7, which instrument
     may be filed of record.

          (h)  In the event request is made of Tenant for written confirmation
     that any proposed transaction is not subject to the rights of first offer
     granted to Tenant pursuant to the provisions of this Section S.7, then if
     Tenant has knowledge of said fact and if such is the case, Tenant, within
     ten (10) days after notice of the proposed transaction and requested
     confirmation, shall execute and deliver to the holder of any interest in
     the Premises requesting said confirmation, a written statement confirming
     that Tenant does not have the right of first offer with respect to said
     proposed transaction.

                                      -8-
<PAGE>
 
          (i)  Except for the Closing Date and the Price and Terms described
     above, Tenant shall purchase the Premises on the terms and conditions set
     forth in the Purchase Contract. Within ten (10) days after Tenant accepts
     Landlord's Price and Terms or Landlord accepts Tenant's Price and Terms,
     Tenant shall deliver to Landlord four (4) copies of the Purchase Agreement
     modified to reflect the Price and Terms, the Closing Date and the property
     to be purchased. Within ten (10) days thereafter, Landlord shall execute
     such Purchase Contract and deliver two (2) execution copies to Tenant.

          (j)  If Landlord sells the Premises pursuant to Section S.7(e) above
     for a price (before deduction for the costs and expenses incurred in
     connection with such sale) ("Sales Price") in excess of the Applicable
     Option Price, then Landlord shall pay to Tenant an amount equal to fifty
     percent (50%) of the Excess Sale Proceeds (as defined below) at the same
     time and in the same manner as such Excess Sale Proceeds are paid to
     Landlord by the purchaser of the Premises. This Section S.7(j) shall not
     apply to any disposition of the Premises described in Section S.7(b). As
     used in this Section S.7(j):

               (i)    "Applicable Option Price" shall mean the Purchase Price
          determined pursuant to Section 3.1 of the Purchase Contract attached
          hereto as Rider E assuming (x) the Closing Date under such Contract
          was the date the Premises was sold by Landlord and (y) the Total
          Project Costs, as such term is used in the Purchase Contract, shall
          not include the sum of (aa) $7,236,000, (bb) the portion of the
          $500,000 Repair Allowance described in Section S.2 of the 1501 Lease
          which has been paid by Landlord and (cc) all other costs expended by
          Landlord to acquire the premises under the 1501 Lease from Tenant
          pursuant to the Purchase and Sale Agreement.

               (ii)   "Excess Sale Proceeds" shall mean the Sale Price less the
          Applicable Option Price and all costs and expenses incurred by
          Landlord to sell the Premises, including without limitation,
          prorations, attorney fees, title insurance and transfer taxes.

          (k)  As used herein "Landlord Affiliate" shall mean any natural person
     or any firm, corporation, partnership, limited liability company,
     association, trust or other entity which, directly or indirectly, controls,
     or is under common control with landlord (or if Landlord is an Illinois
     land trust, the holder of the beneficial interest in such land trust) and
     any firm, corporation, partnership, association, trust or other entity
     which is controlled by Landlord (or if Landlord is an Illinois land trust,
     the holder of the beneficial interest in such land trust). For purposes
     hereof, the term "control" shall mean the possession, directly or
     indirectly, of the power to direct or cause the direction of the management
     and policies of any entity or the power to veto major policy decisions of
     any entity, whether through the ownership of voting securities, by
     contract, or otherwise.

                                      -9-
<PAGE>
                                  WITNESSETH:


                                  ARTICLE 1.
                                GRANT AND TERM

     1.01  Grant of Lease.  Landlord, for and in consideration of the rents
reserved herein and of the covenants and agreements contained herein on the part
of Tenant to be performed, hereby leases to Tenant, and Tenant hereby leases
from Landlord, the Premises for the Term.

     1.02  Possession.  Tenant shall take possession of each Office Space Phase
on the Phase Commencement Date for such Phase. If Tenant takes possession of the
Building or any portion thereof for the conduct of its business prior to the
Phase Commencement Date for such space, all terms and provisions of this Lease
shall apply, including the obligation for the payment of Base Rent and Rent
Adjustments (both terms as hereinafter defined) for the portion of the Building
so occupied by Tenant at that time.

     Based upon Landlord's reasonable estimate of the progress of construction,
Landlord shall notify Tenant of the anticipated Commencement Date not less than
sixty (60) days prior thereto. Not less than five (5) days after the
Commencement Date, Landlord shall deliver to Tenant a factually correct
Commencement Notice in the form attached hereto as Exhibit B, setting forth the
Commencement Date, and the other matters set forth in said form, and Tenant
shall execute and return a copy of such notice to Landlord. The Commencement
Notice shall be conclusive and binding on Tenant as to all matters set forth
therein. Notwithstanding the foregoing, neither Landlord's failure to request
nor Tenant's failure to execute any Commencement Notice shall affect the
determination of the Commencement Date. If the Commencement Date occurs on other
than the first day of a calendar month, Tenant shall pay a proportionate Base
Rent in advance at the monthly rate set forth herein for such partial month, as
well as any Rent Adjustments for such partial month.

     1.03  Lease Year. As used in this Lease, the term "Lease Year" shall mean
(i) if the Commencement Date is the first day of a calendar month, the twelve
(12) month period commencing on the Commencement Date or (ii) if the
Commencement Date is not the first day of a calendar month, the period
commencing on the Commencement Date and ending on the last day of the twelfth
(12th) full calendar month of the Term, and in either case, each succeeding
twelve (12) month period thereafter which falls in whole or in part during the
Term.


                                  ARTICLE 2.
                         CONSTRUCTION OF IMPROVEMENTS

     2.01  Construction of Improvements.  Subject to the terms and conditions
set forth in Sections 2.02 through 2.18, Landlord shall cause the Improvements,
as defined in Section 2.02, to be constructed on the Land.

                                     -10-
<PAGE>
 
     2.02  Landlord's Obligations. Landlord agrees to furnish all of the
material, labor and equipment for the construction of the improvements (the
"Base Building Improvements") specified in the "Outline Specifications for "Base
Building Improvements" attached hereto as Exhibit C and by this reference made a
part hereof. Landlord shall construct the Base Building Improvements in
accordance with the final plans and specifications for the Base Building
Improvements (the "Final Base Building Plans"), which Landlord shall cause to be
prepared in accordance with the "Schedule of Plan Submissions" attached hereto
as Exhibit D and by this reference made a part hereof. In addition, Landlord
agrees to furnish all of the material, labor and equipment for construction of
the Tenant office improvements (the "Office Improvements") in accordance with
final plans and specifications (the "Final Office Plans") which Tenant shall
cause to be prepared in accordance with the Schedule of Plan Submissions. The
term "Improvements" shall mean the Base Building Improvements and the Office
Improvements, collectively. The division of the Improvements between Base
Building Improvements and Office Improvements ("Tenant Improvement Work") is set
forth on attached Exhibit E.  The Improvements shall be constructed in a good
and workerlike manner and in accordance with Applicable Laws, as hereinafter
defined. The Final Base Building Plans and Final Office Plans (collectively, the
"Final Plans") shall be (a) subject to the approval of Landlord and any local
governmental agencies having jurisdiction over the construction of the
Improvements and (b) revised, and the Improvements shall be modified, to
incorporate any revisions thereto required by any governmental agency or
Landlord. Landlord shall submit a cost estimate for the Office Improvements to
Tenant together with a schedule for completing the Improvements which shall set
forth any Tenant Delays and costs attributable thereto that have become apparent
during the designing and pricing of the Improvements.

     2.03  Contractor and Architect. All work involved in the construction and
installation of the Improvements shall be carried out by a general contractor
selected by Landlord (the "Contractor"), under the sole direction of Landlord.
The Contractor shall be subject to Tenant's prior approval, such approval not to
be unreasonably withheld and such approval or disapproval shall be given to
Landlord within five (5) business days after requested by Landlord. Tenant
approves the Contractors listed on attached Exhibit F and by this reference made
a part hereof.

     Tenant shall engage an architect ("Tenant's Architect") licensed to
practice in the State of Illinois, to prepare the Final Office Plans. Tenant and
Tenant's Architect shall cooperate with Landlord, Contractor and Architect to
promote the efficient and expeditious completion of such work. Tenant's
Architect shall be subject to Landlord's reasonable approval.

     2.04  Landlord's Right to Make Changes. Landlord may (i) in preparing the
Final Base Building Plans, depart from the scope of the Outline Specifications
for Base Building Improvements due to reasons other than Changes, provided that
Tenant shall have the right to approve any Landlord Scope Changes materially
affecting the Building and (ii) make changes to the Final Plans provided the
Final Plans as modified, are consistent with the Base Building Improvements.
Landlord shall notify Tenant of any material changes to the Final Plans.
Tenant's consent shall be required for any changes having a value in excess of
$100,000. Tenant shall approve or disapprove such changes within three (3)
business days after Landlord's request for such consent.

                                     -11-
<PAGE>
 
     2.05  Definition of Changes. "Changes" shall mean any revisions to the
Improvements or the Final Plans which are (a) requested by Tenant and approved
by Landlord in Landlord's sole discretion, including, without limitation,
changes from the Outline Specifications for Base Building Improvements
(including any change in the square footage of the Building) which are
incorporated into the Final Plans during the initial preparation thereof, or (b)
required by any governmental agency in order to comply with any statutes,
ordinances, regulations or codes.

     2.06  Costs of Changes. If Landlord approves Changes requested by Tenant,
or if Changes are required by any governmental agency, Landlord shall reasonably
determine any changes in the Costs (as defined herein) of the Improvements and
deliver to Tenant a notice setting forth a pricing schedule (the "Pricing
Schedule") setting forth a schedule of the Costs of the Changes and its non-
binding estimate of any Tenant Delays resulting from such changes. Landlord
shall revise the Pricing Schedule from time to time to reflect any further
Changes since the prior Pricing Schedule. Tenant shall be deemed to have
approved all Costs of Changes in connection with Changes that are required by
any governmental agency in order to comply with any statutes, ordinances,
regulations or codes. In the case of Changes requested by Tenant, Tenant shall
approve or disapprove in writing the Costs of the Changes shown in the Pricing
Schedule or any revised Pricing Schedule within seven (7) days after Landlord
submits the revised Pricing Schedule to Tenant and, if such approval is not
received by Landlord within the applicable seven (7) day period, Tenant shall be
deemed to have disapproved the Costs of such Changes. If Landlord approves
Changes requested by Tenant and Tenant approves the revised Pricing Schedule in
writing, or if Changes are required by a governmental agency, the work to be
performed by Landlord shall include the revisions to the Improvements shown in
the revised Final Plans.

     2.07  Substitution of Materials.  Landlord, at its option, may substitute
for items or materials provided for in the Final Plans, as revised from time to
time, other items or materials of equal or better kind and quality if, in
Landlord's reasonable judgment, the use of the items or materials provided for
in the Final Plans would cause delay in the completion of construction;
provided, however, that any substitutions which will materially and adversely
affect Tenant's use and occupancy of the Premises for its intended purpose shall
only be made with Tenant's prior written consent, which consent shall not be
unreasonably withheld or delayed.

     2.08  Definition of Costs.  As used herein, the term "Costs" shall mean and
refer to all costs expended by Landlord relative to the construction of the
Improvements and acquisition of the Land, which shall include, without
limitation, the costs of equipment, material and labor, contractor's field
overhead and fees, architectural, design and engineering fees, fees and expenses
of architects and other professionals for presentations to governmental
agencies, construction management fees, space studies, working drawings,
governmental agency fees, permit expenses, interest on construction financing
from the date of disbursement until such financing shall be repaid in full at
the rate charged to Landlord by its construction lender, construction loan fees,
insurance premiums, title insurance premiums, testing and inspection costs,
sales and use taxes, permits, plan check fees, impact fees, bonds, zoning costs,
subdivision expenses, infrastructure improvements and donations, Taxes (as
hereinafter defined), closing costs, land acquisition costs, legal expenses,
costs to prepare "as built" plans and documentations for the Building and
materials necessary to properly maintain the Building, and other costs directly
or indirectly related to the construction of the Improvements.

                                     -12-
<PAGE>

     2.09  Payment of Costs. Landlord shall pay the Costs of the work provided
for in the Outline Specifications for Base Building Work and the amount of any
increases in the Costs of the work due to Landlord Scope Changes, and Changes
required by governmental authority which are not related to Tenant Delay or
Changes requested by Tenant or required as a result of Changes requested by
Tenant ("Base Building Governmental Changes"). Within ten (10) days after
receipt from Landlord from time to time of invoices therefor, Tenant shall pay
the amount of any net increases in the Costs of the work provided for in the
Outline Specifications for Base Building Improvements due to (i) Changes other
than Landlord Scope Changes and Base Building Governmental Changes or (ii)
Tenant Delay. Landlord shall contribute Six Million Dollars ($6,000,000) as
Landlord's share of the Costs of the Office Improvements. All Costs of the
Office Improvements in excess of Six Million Dollars ($6,000,000) (the "Excess
Costs") shall be paid by Tenant following Landlord's expenditure of Six Million
Dollars ($6,000,000) for Costs of Office Improvements as follows, subject to
adjustment when the actual Costs of the Office Improvements are finally
determined:

          (a)  The Costs of the Office Improvements in excess of Six Million
Dollars ($6,000,000) shall be paid by the Tenant within ten (10) days of
Tenant's receipt from Landlord of an invoice for such Excess Costs.

          (b)  If the Costs of the Office Improvements are less than Six Million
Dollars ($6,000,000) the difference shall be applied to pay the Costs due to (i)
Changes other than Landlord Scope Changes and Base Building Governmental Changes
and (ii) Tenant Delays, or to reimburse Tenant for such Costs previously paid by
Tenant. Tenant shall not be entitled to any rebate or credit from Landlord or
any abatement of Rent for any portion of such difference not applied to the
Costs of Changes or Tenant Delays because such difference is taken into account
in determining the Base Rent.

     2.10  Tenant's Right to Inspect the Building.  In the event Tenant
desires to inspect the Building prior to the time it is Ready for Occupancy,
Tenant shall so notify Landlord thereof in writing and Landlord shall attempt to
schedule the desired inspection with Contractor or Architect, provided that in
no event shall Tenant's inspection interrupt or interfere with any work then
being performed by Landlord or its contractors or agents at the time of such
inspection.

     2.11  Completion Date for the Building.  Construction of the Improvements
shall be pursued diligently so that portions of the Building shall be Ready For
Occupancy by the dates set forth on attached Exhibit G ("Required Completion
Dates"), subject to extension due to Tenant Delays and Force Majeure Delays. If
the applicable portions of the Building are not Ready for Occupancy on the
Required Completion Dates for reasons other than Tenant Delay or Force Majeure
Delays, then as Tenant's sole remedy for such delay, Tenant shall be entitled to
abate Base Rent, on a per diem basis, as follows: (i) for the first thirty (30)
days that the Ready for Occupancy date is so delayed, one and five tenths (1.5)
days for each day of such delay and (ii) for any period in excess of thirty (30)
days of delay, two (2) days for such day that the Ready for Occupancy date is
delayed. If Landlord believes that it will not be in a position to deliver the
Building Ready for Occupancy on or before the Required Completion

                                     -13-
<PAGE>
 
Date, Landlord shall be required to give Tenant thirty (30) days' advance notice
of the date upon which the Building shall be Ready for Occupancy.

     2.12  Definition of Ready for Occupancy.  Portions of the Building shall be
deemed "Ready for Occupancy" on the date of Substantial Completion (as defined
in Section 2.13) of the Improvements applicable to such portions of the
Building, or if the date of Substantial Completion is delayed due to Tenant
Delay (as hereinafter defined), the date Substantial Completion of the
Improvements applicable to such portions of the Building, would have occurred
but for such Tenant Delay.

     2.13  Punch List.  Not less than five (5) days prior to the Substantial
Completion of the Improvements, Landlord shall notify Tenant of a time and date
for inspection of the Improvements. Following Tenant's receipt of Landlord's
notice of a time and date for inspection of the Improvements, Tenant and
Tenant's Architect shall participate with Architect and Landlord in such
inspection, and Architect shall consult with Tenant's Architect regarding the
date of Substantial Completion and regarding the development by Architect of a
"Punch List" of items that are not yet completed; provided, however, that
Architect's determination of Substantial Completion and the Punch List shall be
conclusive. Tenant shall cause Tenant's Architect to cooperate with Architect in
developing the Punch List. Tenant agrees that, at the request of Landlord from
time to time, Tenant shall initial such Punch List or execute revised Punch
Lists to reflect partial completion of prior Punch List items. Landlord shall
diligently complete as soon as reasonably possible any items of work and
adjustment not completed on the date of Substantial Completion, and in
connection therewith, Landlord may enter into the Building to complete same.
Tenant may complete any Punch List items not completed within ninety (90) days
after date of Substantial Completion unless Landlord's failure to complete such
items was due to Landlord's or contractor's inability to obtain required
materials, Force Majeure Delays or Tenant Delays, Landlord shall reimburse
Tenant for the reasonable costs incurred by Tenant in completing the Punch List
items in accordance with this Section within thirty (30) days after receipt of
Tenant's invoice for such costs. Any costs incurred by Tenant to complete the
Punch List shall be included in the Costs of the Improvements. Such entry by
Landlord, its agents, employees, contractors or representatives for such purpose
shall not constitute an actual or constructive eviction, in whole or in part, or
entitle Tenant to any abatement or diminution of Base Rent or Rent Adjustments,
or relieve Tenant from any of its obligations hereunder, or impose any other
liability, on Landlord, its agents, employees, contractors or representatives.
As used herein, "Substantial Completion" means (i) for the Base Building Work,
the date certified by the architect as the date on which the Base Building
Improvements are substantially complete and (ii) for each Office Space Phase
described in Exhibit G, the date certified by the Architect as the date on which
the Improvements for such Office Space Phase are substantially complete so
Tenant can occupy the Office Space Phase for its normal business activity,
except for normal Punch List items not unreasonably interfering with Tenant's
use of the Office Space Phase and the mechanical, electrical, plumbing, heating,
ventilation and air conditioning systems serving the Office Space Phase are in
good working order.

                                     -14-
<PAGE>
 
     2.14  Contractor's and Landlord's Warranty.  In lieu of all other
warranties and liability by reason of the construction of the Improvements or
otherwise, Landlord and Contractor shall warrant, for a period of one (1) year
from the date that the Building is Ready for Occupancy, that the Building is
free from all defects in materials or workmanship, including latent defects.
Landlord shall assign said Contractor's warranty to Tenant upon completion of
the Improvements and deliver all operation and maintenance manuals to Tenant. At
Tenant's request, Landlord shall enforce any rights it has under the
construction contract or the agreement with Landlord's architect and engineers
with respect to defects in materials or workmanship or design of the Building or
assign such rights to Tenant for enforcement during the Term.

     2.15  Compliance with Law.  Landlord represents and agrees that the Base
Building Improvements shall be designed in compliance with and in conformity to
all lawful requirements, rules, regulations, laws and ordinances of all legally
constituted authorities relating thereto ("Applicable Laws"), including without
limitation all "Environmental Laws" (as such term is hereinafter defined), and
Landlord shall cause Architect to furnish a certificate to Tenant that the Base
Building Improvements have been designed in compliance and conformance with
applicable building codes (i) as a condition to obtaining Tenant's approval of
the Final Base Building Plans and (ii) promptly following substantial completion
of the Improvements. Tenant warrants and agrees that the Office Improvements
shall be designed in compliance with and conformance with all Applicable Laws
and Tenant shall cause Tenant's Architect to furnish a certificate to Landlord
that the Office Improvements have been designed in accordance with applicable
building codes (i) as a condition to obtaining Landlord's approval of the Final
Office Plans and (ii) promptly following substantial completion of the
Improvements. If it becomes necessary to obtain any governmental permit or
approval, other than the customary building permit, in order to construct the
Improvements, Tenant agrees to cooperate fully with Landlord in all respects in
order to obtain the same.

     2.16  Definition of Delays. As used in this Lease:

          (a)  "Tenant Delay" shall mean any delay in Landlord's completion of
the Improvements caused by:

          (i)    Tenant's or Tenant's Architect's failure to deliver or approve
plans within the time periods specified in the Schedule of Plan Submissions;

          (ii)   The Office Improvements are not in compliance with law;

          (iii)  Tenant's failure to approve Landlord's estimates for the Costs
of the Office Improvements or Changes within the time periods specified herein;

          (iv)   Changes requested by Tenant in the Improvements or the Final
Plans, notwithstanding Landlord's subsequent approval of such Changes,
including, without limitation, Changes from the Outline Specifications for Base
Building Improvements which are incorporated into the Final Base Building Plans
during the initial preparation thereof;

          (v)    Tenant's selection of so-called "long lead time items" whether
as to materials, finishes or installations;

                                     -15-
<PAGE>
 
          (vi)   Tenant's failure to complete any work which Tenant is obligated
to perform and which is required for the issuance of a certificate of occupancy,
including, but not limited to, fire alarm installation in the Building; and

          (vii)  Any other delays caused by or significantly contributed to by
Tenant, Tenants' Architect, or their officers, employees, agents, contractors,
licensees or their representatives.

     (b)  "Force Majeure Delay" shall mean any delay in the completion of the
Improvements which is attributable to any: (1) actual delay or failure to
perform attributable to any regional or industry-wide strike, lockout or other
labor or industrial disturbance (whether or not on the part of the employees of
either party hereto), civil disturbance, act of a public enemy, war, riot,
sabotage, blockade, embargo, inability to secure customary materials, supplies
or labor through ordinary sources by reason of regulation or order of any
government or regulatory body; (2) delay attributable to the failure of Landlord
to secure building permits and approvals within the same time period that
normally prevailed for obtaining such permits at the time this Lease was
negotiated; (3) delay in completing the Final Plans because of changes in any
Applicable Laws or the interpretation thereof; or (4) delay attributable to
lightning, earthquake, fire, storm, hurricane, tornado, flood, washout,
explosion, or any other similar industry-wide or Building-wide cause beyond the
reasonable control of the party from whom performance is required, or any of its
contractors or other representatives.

     2.17  Obligations of the Architects. Architect and Tenant's Architect,
within the scope of their respective duties, shall (a) be responsible for the
preparation of plans and specifications described in Section 2.02 on or before
the dates set forth in the Schedule of Plan Submissions, (b) cooperate with
Landlord, Contractor and Tenant to enable completion of the Improvements in
accordance with the Final Plans, including the preparation of drawings for the
modification of those Final Plans if Landlord and Tenant so require, and (c)
deliver a statement to Landlord, Tenant and any lender of Landlord upon
completion of the Improvements and from time to time during construction at the
time of each construction draw, as to the Improvements provided for in the Final
Plans prepared by such architect, in the form required by Landlord's lender,
that the Improvements have been completed in a good and workmanlike manner in
substantial compliance with the Final Plans so prepared by Architect or Tenant's
Architect (as the case may be) and all governmental regulations and ordinances.
Landlord and Tenant shall deliver to each other evidence of errors and omissions
insurance coverage carried by their respective architects with limits of
liability of not less than Two Million Dollars ($2,000,000).

     2.18  Limitation of Landlord's Construction Obligation. Except as expressly
set forth in this Lease, Landlord has no agreement with Tenant and has no
obligation to do any other work with respect to the Premises. Any other work in
the Premises which Tenant may be permitted by Landlord to perform prior to
commencement of the Term shall be done at Tenant's sole cost and expense and in
accordance with the terms and conditions of the Lease, and shall be subject to
such requirements as Landlord deems reasonably necessary or desirable. Any
additional work or alterations to the Premises desired by Tenant after the
commencement of the Term shall be subject to the provisions of the Lease.

                                     -16-
<PAGE>
 
                                  ARTICLE 3.
                                   BASE RENT

     3.01  Base Rent. Tenant shall pay an annual base rent (hereinafter referred
to as "Base Rent") to Landlord for the Premises in the amount stipulated in the
Schedule, payable in equal monthly installments in the amount stipulated in the
Schedule, in advance on the first day of the Term and on the first day of each
calendar month thereafter of the Term, and at the same rate for fractions of a
month if the Term begins on any date except the first day of a calendar month or
ends on any day except the last day of a calendar month.

     3.02  Manner of Payment.  Base Rent, Tax Rent Adjustments (as hereinafter
defined), Tax Rent Adjustment Deposits (as hereinafter defined) and all other
amounts becoming due from Tenant to Landlord hereunder (hereinafter collectively
referred to as "Rent") shall be paid in lawful money of the United States to
Landlord at the office of Landlord, or as otherwise designated from time to time
by written notice from Landlord to Tenant. The payment of Rent hereunder is
independent of each and every other covenant and agreement contained in this
Lease, and Rent shall be paid without any setoff, abatement, counterclaim or
deduction whatsoever except as may be expressly provided herein.


                                  ARTICLE 4.
                                     TAXES

     4.01  Obligation to Pay Tax Rent Adjustments. In addition to paying Base
Rent specified in Section 3.01, Tenant shall also pay, as additional rent, the
amount of the Taxes due for each Adjustment Year (hereinafter referred to as
"Tax Rent Adjustments"). Tenant agrees and acknowledges that Landlord has made
no representation, warranty or guaranty relating to the amount of Taxes. Tenant
has not relied upon any statements or representations of Landlord or any agent
or affiliate of Landlord in regard to Taxes in executing this Lease and agreeing
to perform the terms and covenants hereof and shall make no claim against
Landlord based thereon.

     4.02  Definitions.  As used in this Lease,

          (a)  "Adjustment Year" shall mean the calendar year in which the first
Phase Commencement Date occurs and each subsequent calendar year, all or any
part of which falls within the Term.

          (b)  "Taxes" shall mean real estate taxes, general or special
assessments, sewer rents, rates and charges, transit and transit district taxes,
taxes based upon the receipt of rent, and any other federal, state or local
governmental charge, whether general, special, ordinary or extraordinary (but
not including income or franchise taxes or any other taxes imposed upon or
measured by Landlord's income or profits, except as provided herein), which may
now or hereafter be levied, assessed or imposed against the Real Property.

                                     -17-
<PAGE>
 
     Notwithstanding anything contained in this clause (b) to the contrary:

               (i)    If at any time the method of taxation then prevailing is
          altered so that any new or additional tax, assessment, levy,
          imposition or charge or any part thereof is imposed upon Landlord in
          place or partly in place of any such Taxes or contemplated increase
          therein, or in addition to Taxes, and is measured by or is based in
          whole or in part upon the Real Property or the rents or other income
          therefrom, then all such new taxes, assessments, levies, impositions
          or charges or part thereof, to the extent that they are so measured or
          based, shall be included in Taxes levied, assessed or imposed against
          the Real Property to the extent that such items would be payable if
          the Real Property were the only property of Landlord subject thereto
          and the income received by Landlord from the Real Property were the
          only income of Landlord.

               (ii)   Notwithstanding the year for which any such taxes or
          assessments are levied, (A) in the case of taxes or special
          assessments which may be paid in installments, the amount of each
          installment, plus any interest payable thereon, paid during a calendar
          year shall be included in Taxes for that year and (B) if any taxes or
          assessments payable during any calendar year shall be computed with
          respect to a period in excess of twelve (12) calendar months, then
          taxes or assessments applicable to the excess period shall be included
          in Taxes for that year. Except as provided in the preceding sentence,
          all references to Taxes "for" a particular year shall be deemed to
          refer to taxes levied, assessed or otherwise imposed for such year
          without regard to when such taxes are payable.

               (iii)  Taxes shall also include any personal property taxes
          (attributable to the calendar year in which paid) imposed upon the
          furniture, fixtures, machinery, equipment, apparatus, systems and
          appurtenances which are components of the Real Property.

          (c)  "Real Property" means the Building and Land.

     4.03  Payments of Tax Rent Adjustments. Tenant shall pay Tax Rent
Adjustments to Landlord as follows:

          (a)  Promptly after receipt of a statement from the appropriate
authority for any installment (including any estimated installment) of Taxes
payable during an Adjustment Year, Landlord shall furnish Tenant a written
notice ("Tax Installment Statement") setting forth the amount of Taxes shown to
be due on such statement of Taxes. Within fifteen (15) days after receipt of
Landlord's Tax Installment Statement, Tenant shall pay to Landlord the Tax
Adjustment shown as due on the Tax Installment Statement.

          (b)  Prior to the end of the final Adjustment Year, Landlord shall
deliver to Tenant a written notice ("Final Year Tax Notice") setting forth
Landlord's reasonable estimate, forecast or projection (the "Tax Projection") of
Taxes (1) applicable to any prior Adjustment Year which have not yet been paid
by Tenant to Landlord and (2) applicable to such final

                                     -18-
<PAGE>
 
Adjustment Year. Within fifteen (15) days following Landlord's delivery of the
Final Year Tax Notice, Tenant shall pay Landlord the Tax Projection shown on the
Final Year Tax Notice. Any Tax Projection paid by Tenant for any Adjustment Year
shall be applied as a credit against the amounts owed by Tenant for such
Adjustment Year pursuant to subparagraph (a) above, provided that if the Taxes
for such Adjustment Year are payable in installments, the Tax Projection applied
as a credit shall be divided equally among the installments to be paid by
Tenant.

          (c)  If any First Mortgagee (as defined in Section 18.01) requires
periodic deposits for Taxes or other security for the payment of Taxes, Tenant
shall pay such periodic deposits to Landlord when and as required by the First
Mortgagee or provide such security to the First Mortgagee. Any deposits made by
Tenant for an Adjustment Year shall be applied as a credit against Taxes payable
by Tenant pursuant to subparagraph (a) above and any Tax Projection required
under subparagraph (b) above. Landlord shall use reasonable efforts to exclude
from the First Mortgage documents any requirement for periodic deposits of Taxes
or other security for the payment of Taxes. If Landlord is unable to eliminate
the requirement for periodic deposits of Taxes, Landlord shall use reasonable
efforts to have such deposits held in an interest bearing account with the
interest to be held for Tenant's account.

     4.04  Proration and Survival.  With respect to any Adjustment Year which
does not fall entirely within the Term, Tenant shall be obligated to pay as Tax
Rent Adjustments for such Adjustment Year only a pro rata share of Tax Rent
Adjustments as herein determined, based upon the number of days of the Term
falling within the Adjustment Year. Following expiration or termination of this
Lease, Tenant shall pay any Tax Rent Adjustments due to Landlord within fifteen
(15) days after the date of each Landlord's Statement sent to Tenant. Without
limitation of other obligations of Tenant which shall survive the expiration of
the Term, the obligation of Tenant to pay Tax Rent Adjustments provided for in
this Article 4 accruing during the Term shall survive the expiration or
termination of this Lease.


                                  ARTICLE 5.
                                USE OF PREMISES

     Tenant shall use and occupy the Premises for general office purposes and
uses incidental thereto permitted under law and for no other use or purpose.


                                   ARTICLE 6.
                                   UTILITIES

     6.01  Payment for Utilities.  Tenant will pay, when due, all charges of
every nature, kind or description for utilities and other services furnished to
the Premises during the Term or chargeable against the Premises with respect to
the Term, including all charges for water, sewage, heat, gas, light, garbage,
electricity, telephone, steam, power, or other public or private utility
services. Tenant shall also pay for all utilities or services at the Premises
used by it or

                                     -19-
<PAGE>
 
its agents, employees or contractors prior to commencement of the Term.

     6.02  Utilities.  Tenant shall be responsible for contracting directly with
all suppliers of utility services. In the event that any charge or fee is
required by the State of Illinois, or by any agency, subdivision or
instrumentality thereof, or by any utility company or other entity furnishing
services or utilities to the Premises, as a condition precedent to furnishing or
continuing to furnish utilities or services to the Premises, such charge or fee
shall be deemed to be a utility charge payable by Tenant. The provisions of this
paragraph shall include, but shall not be limited to, any charges or fees for
present or future water or sewer capacity to serve the Premises, any charges for
the underground installation of gas or other utilities or services, and other
charges relating to the extension of or change in the facilities necessary to
provide the Premises with adequate utility services to the extent such
installations or extensions are not reflected in the Final Plans or any Changes
thereto. Tenant may elect to cause the Final Plans to provide for separate
metering of utilities to various portions of the Building. If Tenant makes such
an election, the Costs of such separate metering shall be paid in the same
manner as all other Costs of the Office Improvements by Tenant. In the event
that Landlord has paid any such charge or fee after the date hereof, Tenant
shall reimburse Landlord for such utility charge upon Landlord's demand
therefor. The inability of Tenant to obtain, or any stoppage of, the utility
services referred to in this Article 6 resulting from any cause shall not
constitute a constructive eviction, shall not make Landlord liable in any
respect for damages to any person, property or business, and shall not entitle
Tenant to any abatement of Rent or other relief from any of Tenant's obligations
under this Lease.


                                  ARTICLE 7.
                   CONDITION, CARE AND OPERATION OF PREMISES

     7.01  Condition of Premises.  Tenant's taking possession of the Premises or
any portion thereof shall be conclusive evidence against Tenant that the portion
of the Premises for which possession was taken in good order and satisfactory
condition, subject to Landlord's obligation to complete Punch List items and
latent defects in the Improvements.

     7.02  Tenant's Maintenance and Operation Obligations.  Tenant shall keep
the Premises, including any improvements thereto by Tenant, in good order and in
a safe, neat and clean condition and will take all action and will make, except
as otherwise stated herein, all structural and nonstructural, foreseen and
unforeseen and ordinary and extraordinary changes, repairs and replacements.
Tenant's obligations under this Article shall include without limitation all
repairs and replacements to the roof, structure, supports, foundation, floors,
gutters, downspouts, windows, doors, exterior walls, parking areas, and
sidewalks, the maintenance of the landscaping on the Premises in a neat and
attractive condition and the removal of all snow and ice from the walkways,
parking areas and drives on the Premises and the operation, maintenance and
repair of all building systems. It is the intent of the parties hereto, that
Tenant shall bear all responsibility for the maintenance, upkeep and replacement
of the Premises, Building and Land. Tenant's operation, maintenance and repair
of the Premises shall be conducted in accordance with the standards set forth on
Rider F attached hereto and made a part

                                     -20-
<PAGE>
 
hereof. In the event Tenant fails to commence promptly and pursue diligently the
performance of such maintenance or the making of such repairs or replacements,
then Landlord, at its option, may perform such maintenance or make such repairs
and replacements and Tenant shall reimburse Landlord, on demand after Tenant
receives an invoice therefor, the cost thereof plus a fee equal to fifteen
percent (15%) of the actual costs to cover the overhead. No representations
respecting the condition of the Premises or the Building have been made by
Landlord to Tenant except as specifically set forth in this Lease.
Notwithstanding the foregoing to the contrary, Tenant shall not have any
obligation to repair or replace any item covered by Landlord's and Contractor's
warranty described in Section 2.14. If Tenant incurs any costs in connection
with its maintenance and repair obligations with respect to the Base Building
Improvements during the last five (5) years of the Term or any Extended Term
(last seven (7) years in the case of a replacement of the roof of the Building)
which under generally accepted accounting principles ("GAAP") is required to be
capitalized and depreciated ("Base Building Capital Costs") and the Term of this
Lease expires prior to the end of the applicable depreciation period under GAAP,
then upon expiration of this Lease, Landlord shall pay to Tenant a pro rata
portion of such costs based on the ratio of the portion of the depreciation
period not included within the Term to the total depreciation period. Tenant
shall not incur any Base Building Capital Costs without Landlord's prior written
consent.

     7.03  Work Performed by Tenant.  All repairs made by Tenant pursuant to
Section 7.02 shall be performed in a good and workmanlike manner by contractors
or other repair personnel selected by Tenant and approved by Landlord. All
contracts for such maintenance and repair services shall be subject to
Landlord's reasonable approval. In no event shall such work be done for
Landlord's account or in a manner which allows any liens to be filed against the
Building or the Premises in violation of Article 27.

     7.04  Janitorial Service.  Tenant shall be responsible for providing
janitorial service for the Premises at Tenant's sole cost and expense in
accordance with the standards attached hereto as Rider C. Such janitorial
service shall be performed by a company and pursuant to a contract reasonably
satisfactory to Landlord.

     7.05  Waste.  Tenant shall not do or suffer any waste or damage,
disfigurement or injury to the Premises, or any improvements hereafter erected
thereon, or to the fixtures or equipment therein, or permit or suffer any
overloading of the floors or other use of the improvements that would place an
undue stress on the same or any portion thereof beyond that for which the same
was designed.


                                  ARTICLE 8.
                              RETURN OF PREMISES

     8.01  Surrender of Possession.  At the termination of this Lease by lapse
of time or otherwise, or upon termination of Tenant's right of possession
without termination of this Lease, Tenant shall surrender possession of the
Premises to Landlord and deliver all keys to the Premises to Landlord and make
known to Landlord the combination of all locks of vaults then

                                     -21-
<PAGE>
 
remaining in the Premises, and, subject to the following paragraph, shall return
the Premises and all equipment and fixtures of Landlord therein to Landlord in
as good condition as when Tenant originally took possession or, if there is a
Punch List, when the work provided for in the Punch List is completed, ordinary
wear, and damage resulting from the act of Landlord or its employees and agents
excepted, failing which Landlord may restore the Premises and such equipment and
fixtures to such condition and Tenant shall pay the cost thereof to Landlord on
demand.

     8.02  Installations and Additions.  All installations, additions,
partitions, hardware, light fixtures, non-trade fixtures and improvements,
whether temporary or permanent, except movable furniture and equipment belonging
to Tenant, in or upon the Premises, whether placed there by Tenant or Landlord,
shall be Landlord's property and shall remain upon the Premises, all without
compensation, allowance or credit to Tenant; provided, however, that if prior to
such termination or within ten (10) days thereafter Landlord so directs by
notice, Tenant, at Tenant's sole cost and expense, shall promptly remove such of
the installations, additions, partitions, hardware, light fixtures, non-trade
fixtures and improvements placed in the Premises by Tenant as are designated in
such notice and repair any damage to the Premises caused by such removal,
failing which Landlord may remove the same and repair the Premises and Tenant
shall pay the cost thereof to Landlord on demand.

     8.03  Trade Fixtures and Personal Property.  Tenant also shall remove
Tenant's furniture, machinery, safes, trade fixtures and other items of movable
personal property of every kind and description from the Premises and restore
any damage to the Premises caused thereby, such removal and restoration to be
performed prior to the end of the Term or within ten (10) days following
termination of this Lease or Tenant's right of possession, whichever is earlier.
If Tenant fails to remove such items, Landlord may do so and thereupon the
provisions of Section 17.06 shall apply and Tenant shall pay to Landlord upon
demand the cost of removal and of restoring the Premises.

     8.04  Survival.  All obligations of Tenant under this Article shall survive
the expiration of the Term or earlier termination of this Lease.


                                  ARTICLE 9. 
                                 HOLDING OVER

     Tenant shall pay Landlord for each day Tenant retains possession of the
Premises or any part thereof after termination of this Lease, by lapse of time
or otherwise, or of Tenant's right to possession of the Premises, an amount
which is double the amount of Base Rent and Rent Adjustments for a day based on
the annual rate of Base Rent set forth in Section 3.01 and on the Rent
Adjustments provided for in Article 4 in effect immediately prior to such
termination, and Tenant shall also pay all direct damages sustained by Landlord
by reason of such retention. Acceptance by Landlord of rent after such
termination, of itself, shall not constitute a renewal. Nothing contained in
this Section shall be construed or shall operate as a waiver of Landlord's right
of reentry or any other right or remedy of Landlord.

                                     -22-
<PAGE>
 
                                  ARTICLE 10.
                             RULES AND REGULATIONS

     Tenant agrees to observe and not to interfere with the rights reserved to
Landlord contained in Article 11 and agrees, for itself, its employees, agents,
contractors, invitees and licensees, to comply with the rules and regulations
set forth in Rider B attached to this Lease and made a part hereof and such
other rules and regulations as may be adopted by Landlord pursuant to Section
11.01(e) of this Lease. Any violation by Tenant of any of the rules and
regulations contained in Rider B or any other Section of this Lease, or as may
hereafter be adopted by Landlord pursuant to Section 11.01(e) of this Lease, may
be restrained; but whether or not so restrained, Tenant acknowledges and agrees
that it shall be and shall remain liable for all damages, loss, costs and
expenses resulting from any violation by Tenant of any of said rules and
regulations.


                                  ARTICLE 11.
                          RIGHTS RESERVED TO LANDLORD

     11.01  Rights Reserved to Landlord.  Landlord reserves the following
rights, exercisable without notice and without liability to Tenant for damage or
injury to property, person or business and without effecting an eviction or
disturbance of Tenant's use or possession or giving rise to any claim for setoff
or abatement of Rent or affecting any of Tenant's obligations under this Lease:

          (a)  Except for portions of the Premises designated by Tenant as
"secured areas" on floor plans, delivered to Landlord, to retain at all times,
and to use in appropriate instances, pass keys to the Premises;

          (b)  Upon reasonable advance written or telephone notice, to exhibit
the Premises at reasonable hours, and to decorate, remodel, repair, alter or
otherwise prepare the Premises for reoccupancy at any time after Tenant vacates
or abandons the Premises;

          (c)  To enter the Premises at reasonable hours, upon reasonable prior
notice and for reasonable purposes, including inspection, subject to Tenant's
reasonable security restrictions;

          (d)  To make any repairs, alterations, improvements and additions in
and about the Building and the Premises during ordinary business hours and, if
Tenant desires to have such work done during other than business hours, Tenant
shall pay all overtime and additional expenses resulting therefrom; and

          (e)  From time to time to make and adopt such reasonable rules and
regulations, in addition to or other than or by way of amendment or modification
of the rules and regulations contained in Rider B or other Sections of this
Lease, which are not inconsistent

                                     -23-
<PAGE>
 
with the Terms of this Lease for the protection and welfare of the Building as
Landlord may determine, and Tenant agrees to abide by and comply with all such
rules and regulations.


                                  ARTICLE 12.
                                  ALTERATIONS

     Tenant shall not make, without the prior written consent of Landlord, any
alterations, additions or improvements to the Premises. Notwithstanding the
foregoing, Landlord's consent shall not be required for normal decorating work
such as painting and installation of wall coverings and carpeting. Landlord
shall not unreasonably withhold or delay its consent to alterations, additions
or improvements to the Building which do not affect the exterior, or structural
portions of the Building or the base building mechanical, electrical, plumbing,
elevator, security or other systems in the Building. If Landlord consents to
such alterations, additions or improvements, before commencement of the work or
delivery of any materials onto the Premises or into the Building, Tenant shall
furnish to Landlord, for its approval, plans and specifications, names and
addresses of contractors, copies of contracts, necessary permits and licenses,
and instruments of indemnification against any and all claims, costs, expenses,
damages and liabilities which may arise in connection with such work, all in
such form, substance and amount as may be satisfactory to Landlord. In addition,
prior to commencement of any such work or delivery of any materials into the
Premises, Tenant shall provide Landlord with appropriate evidence of Tenant's
ability to pay for such work and materials in full. All alterations, additions
and improvements shall be installed in a good, workerlike manner and only new,
high-grade materials shall be used. All such work shall be done only by
contractors or mechanics reasonably approved by Landlord and shall be subject to
Landlord's scheduling requirements and regulations. Tenant further agrees to
hold Landlord harmless from any and all liabilities of every kind and
description which may arise out of or be connected in any way with said
alterations, additions or improvements. Before commencing any work in connection
with such alterations, additions or improvements, Tenant shall furnish Landlord
with certificates of insurance from all contractors performing labor or
furnishing materials insuring Landlord against any and all liabilities which may
arise out of or may be connected in any way with said alterations, additions or
improvements. Tenant shall permit Landlord to supervise construction operations
in connection with the foregoing work if Landlord requests to do so. Tenant
shall pay the cost of all such alterations, additions and improvements, as well
as the cost of decorating the Premises occasioned by such alterations, additions
and improvements, including the cost of labor and materials, contractors'
profit, overhead, general conditions and a reasonable fee to Landlord. Upon
completing any alterations, additions or improvements, Tenant shall furnish
Landlord with (i) contractors' affidavits in form required by law, and full and
final waivers of lien and receipted bills covering all labor and materials
expended and used and (ii) "as built" or record drawings showing all
alterations, additions and improvements to the Premises. All alterations,
additions and improvements shall comply with all insurance requirements and with
all city and county ordinances and regulations and with the requirements of all
state and federal statutes and regulations.

                                     -24-
<PAGE>
 
                                 ARTICLE 13. 
                           ASSIGNMENT AND SUBLETTING

     13.01  Assignment and Subletting.  Without the prior written consent of
Landlord in each instance and subject to Sections 13.08 and 13.09 below, Tenant
shall not (a) assign, transfer, mortgage, pledge, hypothecate or encumber or
subject to or permit to exist upon or be subjected to any lien or charge, this
Lease or any interest under it; (b) allow to exist or to occur any transfer of
or lien upon this Lease or Tenant's interest herein by operation of law; (c)
sublet the Premises or any part thereof; or (d) permit the use or occupancy of
the Premises or any part thereof for any purpose not provided for under Article
5 of this Lease or by anyone other than Tenant and Tenant's employees. Landlord
has the absolute right to withhold its consent without giving any reason
whatsoever, except as expressly provided herein to the contrary. In no event
shall this Lease be assigned or assignable by voluntary or involuntary
bankruptcy proceedings or otherwise, and in no event shall this Lease or any
rights or privileges hereunder be an asset of Tenant under any bankruptcy,
insolvency or reorganization proceedings.

     13.02  Rentals Based on Net Income.  Without limiting the generality of the
foregoing provisions of this Article, Tenant expressly covenants and agrees not
to enter into any lease, sublease, license, concession or other agreement for
use, occupancy or utilization of the Premises which provides for rental or other
payment for such use, occupancy or utilization based in whole or in part on the
net income or profits derived by any person from the property leased, used,
occupied or utilized (other than an amount based on a fixed percentage or
percentages of receipts or sales), and that any such purported lease, sublease,
license, concession or other agreement shall be absolutely void and ineffective
as a conveyance of any right or interest in the possession, use, occupancy or
utilization of any part of the Premises.

     13.03  Tenant to Remain Obligated.  Consent by Landlord to any assignment,
subletting, use, 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, or be deemed to be a consent to or relieve Tenant
from obtaining Landlord's consent to any subsequent assignment, transfer, lien,
charge, subletting, use or occupancy. Tenant shall pay all of Landlord's costs,
charges and expenses, including reasonable attorneys' fees, incurred in
connection with any assignment, transfer, lien, charge, subletting, use or
occupancy made or requested by Tenant. Tenant agrees that all advertising by
Tenant or on Tenant's behalf with respect to the assignment of this Lease or
subletting of space must be approved in writing by Landlord prior to publication
which approval shall not be unreasonably withheld or delayed.

     13.04  Landlord's Consent. Tenant shall advise Landlord, by written notice
("Tenant Notice"), of its intention from, on and after a stated date (which
shall not be less than sixty (60) days after the date of Tenant's notice) to
assign this Lease or to sublet any part or all of the Premises for any part of
the Term. Tenant's notice shall state the name and address of the proposed
subtenant or assignee, and a true and complete copy of the proposed sublease or
assignment and sufficient information to permit Landlord to determine the
financial responsibility and character of the proposed subtenant or assignee
shall be delivered to Landlord with said notice. Landlord will not withhold its
consent unreasonably to Tenant's assignment of this Lease

                                     -25-
<PAGE>
 
or Tenant's subletting the space covered by its notice. Landlord shall not be
deemed to have withheld its consent unreasonably to a sublease of part or all of
the Premises or an assignment of this Lease if its consent is withheld because:
(a) Tenant is then in Default hereunder; (b) any notice of termination of this
Lease or termination of Tenant's possession is given under Article 17; (c) the
portion of the Premises which Tenant proposes to sublease, including the means
of ingress thereto and egress therefrom and the proposed use thereof, and the
remaining portion of the Premises will violate any city, state or federal law,
ordinance or regulation, including, without limitation, any applicable building
code or zoning ordinances; (d) the proposed use of the Premises by the subtenant
or assignee does not conform with the use permitted by Article 5; (e) in the
reasonable judgment of Landlord, the proposed subtenant or assignee is of a
character or is engaged in a business which would be deleterious to the
reputation of the Building, or the subtenant or assignee is not sufficiently
financially responsible to perform its obligations under the proposed sublease
or assignment; (f) the sublessee's or assignee's business is likely to cause
greater wear and tear to the Premises than occasioned by Tenant's use or (g) the
proposed subtenant or assignee is a government or a government agency; provided,
however, that the foregoing are merely examples of reasons for which Landlord
may withhold its consent and shall not be deemed exclusive of any permitted
reasons for reasonably withholding consent, whether similar to or dissimilar
from to the foregoing examples. Landlord shall either approve or disapprove a
proposed assignment or sublease within thirty (30) days after receipt of the
information and documents described in the second sentence of this Section
13.04.

     13.05  Profits.  If Tenant, having first obtained Landlord's consent to any
sublease or assignment, or if Tenant or a trustee in bankruptcy for Tenant
pursuant to the Bankruptcy Code, assigns this Lease or sublets the Premises, or
any part thereof, at a rental or for other consideration in excess of the Rent
or pro rata portion thereof due and payable by Tenant under this Lease, then
Tenant shall pay to Landlord as additional rent fifty percent (50%) of any such
excess rent or other monetary consideration immediately upon receipt under any
such assignment or, in the case of a sublease, (a) on the first day of each
month during the term of any sublease the excess of all rent and other
consideration due from the subtenant for such month over the Rent then payable
to Landlord pursuant to the provisions of this Lease for said month (or if only
a portion of the Premises is being sublet, the excess of all rent and other
consideration due from the subtenant for such month over the portion of the Rent
then payable to Landlord pursuant to the provisions of this Lease for said month
which is allocable on a square footage basis to the space sublet) and (b)
immediately upon receipt thereof, any other consideration realized by Tenant
from such subletting; it being agreed, however, that Landlord shall not be
responsible for any deficiency if Tenant assigns this Lease or sublets the
Premises or any part thereof at a rental less than that provided for herein.
Notwithstanding the foregoing, Tenant shall not be required to pay Landlord any
amounts pursuant to this Section 13.05 until the amount of the excess rent and
other consideration received by Tenant equals the reasonable out of pocket costs
incurred by Tenant in entering into such sublease or assignment including
without limitation brokers' and attorneys' fees, advertising costs, tenant
buildout costs and construction allowances. The provisions of this Section 13.05
shall not apply to an assignment or sublease described in Sections 13.08 or
13.09 which does not require Landlord's consent.

                                     -26-
<PAGE>
 
     13.06  Assignee to Assume Obligations. If Tenant assigns this Lease as
permitted herein, the assignee shall expressly assume all of the obligations of
Tenant hereunder in a written instrument satisfactory to Landlord and furnished
to Landlord not later than fifteen (15) days prior to the effective date of the
assignment. If Tenant subleases the Premises as permitted herein, Tenant shall
obtain and furnish to Landlord, not later than fifteen (15) days prior to the
effective date of such sublease and in form satisfactory to Landlord, the
written agreement of such subtenant to the effect that the subtenant will attorn
to Landlord, at Landlord's option and written request, in the event this Lease
or Tenant's right to possession of the Premises terminates before the expiration
of the sublease.

     13.07  Change of Control.  Notwithstanding anything to the contrary in this
Article, except as provided in 13.08 below, any change during the Term of this
Lease of the ownership of the shares of stock which constitute control of Tenant
other than by reason of gift or death shall be deemed an assignment of this
Lease and shall be subject to the provisions of this Article 13. The term
"control" as used herein means the power, directly or indirectly, to direct or
to cause the direction of the management or policies of Tenant.

     13.08  Transfer By Merger or Sale or To an Affiliate.

          (a)  Tenant shall have the right, subject to the terms and conditions
hereinafter set forth, without the consent of Landlord, to (i) assign, its
interest in this Lease to any corporation or other entity which is a successor
to Tenant either by reincorporation in another jurisdiction, merger or
consolidation, (ii) assign its interest in this Lease to a purchaser of all or
substantially all of Tenant's assets (provided such purchaser shall have also
assumed substantially all of Tenant's liabilities) or Tenant's stock, or (iii)
assign its interest in this Lease or sublease all or any portion of the Premises
to a Tenant Affiliate, all upon the condition that in each case (x) the
principal purpose of such assignment or sublease is not the acquisition of
Tenant's interest in this Lease (except if such assignment or sublease is made
to an Affiliate and is made for a valid intracorporate business purpose and is
not made to circumvent the provisions of Section 13.1 of this Article), (y) any
such assignee shall have a net worth and annual income and cash flow which shall
meet the requirements set forth in Section 13.08(b) below and (z) any such
assignee or subtenant shall consent, in writing, to the exclusive jurisdiction
of the courts of Illinois and the Federal courts located in the County of Cook,
State of Illinois. Tenant shall, within ten (10) business days after execution
thereof, deliver to Landlord (A) if an assignment, a duplicate original
instrument of assignment in form and substance reasonably satisfactory to
Landlord, duly executed by Tenant, (B) if applicable, evidence satisfactory to
Landlord establishing compliance by the assignee or subtenant with the net
worth, annual income and cash flow requirements of clause (z) above, (C) if an
assignment, an instrument in form and substance reasonably satisfactory to
Landlord, duly executed by the assignee, in which such assignee shall assume
observance and performance of, and agree to be personally bound by, all of the
terms, covenants and conditions of this Lease on Tenant's part to be observed
and performed and (D) if a sublease, a duplicate original sublease in form and
substance reasonably satisfactory to Landlord, duly executed by Tenant and the
subtenant.

                                     -27-
<PAGE>
 
          (b)  As a condition precedent to any assignment which shall otherwise
be permitted under Section 13.08(a) above, such proposed assignee or subtenant
shall have as of the effective date of such assignment or subletting:

               (i)    (A)  an excess of total assets (including intangible
          assets) over total liabilities of not less than One Hundred Twenty-
          Five Million Dollars ($125,000,000.00), provided that the assets
          (other than intangible assets) are not less than One Hundred Million
          Dollars ($100,000,000.00);

                      (B)  a ratio of current assets to current liabilities of
          not less than two (2) to one (1); and

                      (C)  an excess of (y) annual gross cash receipts (other
          than from a financing, sale of an equity interest in such assignee or
          guarantor, or sale of long-term assets), over (z) the sum, without
          duplication, of annual cash operating expenses and annual debt service
          payments and regularly scheduled amortization of principal (other than
          so-called "balloon" payments of principal due at maturity) due on all
          outstanding indebtedness, of not less than two (2) times the annual
          Rent due hereunder for each period; or

               (ii)   a bond rating of "AA" from Standard & Poor's or "AA" from
          Moody's as of the date of such assignment and as of the first
          anniversary of such assignment; or

               (iii)  in the case of an insurance company, a "Best's Rating of
          "A" and a "Financial Size Category" of at least "VIII" in Best's
          Insurance Guide as of the date of such assignment and as of the first
          anniversary of such assignment; or

               (iv)   in the case of any national, foreign or state chartered
          commercial bank not rated by Standard & Poor's or Moody's, (y) total
          assets in excess of One Billion Dollars ($1,000,000,000.00) and (x)
          net cash flow from operations of not less than five (5) times the
          annual Rent due hereunder, and be in compliance with all applicable
          laws and regulations dealing with capital adequacy, as of the date of
          such assignment and at the end of the twelve (12) month period
          subsequent to the date of such assignment.

     All financial criteria set forth in this Section 13.08(b) shall be
determined in accordance with generally accepted accounting principles
consistently applied (or its equivalent in the case of non-U.S. entities) and
based upon annual reports (or fiscal year-end financial statements) of such
assignee or guarantor certified by an independent public accounting firm.

          (c)  A Tenant Affiliate shall mean any person, corporation or other
entity which controls or is controlled by or is under common control with
Tenant. As used herein, "control" shall mean the same meaning as set forth in
Section 13.07.

                                     -28-
<PAGE>
 
     13.09  Sublease with Customers.  Tenant shall have the right, without the
consent of Landlord, to sublease portions of the Premises to customers and
clients of Tenant in connection with the provision of Tenant's services to such
customers and clients on the condition that (a) the principal purpose of such
sublease is not the acquisition of Tenant's interest in this Lease and (b) no
more than twenty-five percent (25%) of the Premises shall be covered by
subleases described in this Section 13.09.

     13.10  Restrictions on Assignment and Sublease.  Notwithstanding anything
in this Lease to the contrary, Tenant may not assign this Lease to any person or
entity or sublease substantially all the Premises to any person or entity unless
Tenant also assigns the 1501 Lease to the same person or entity or subleases
substantially all the Premises under the 1501 Lease to the same person or
entity.


                                  ARTICLE 14.
                 WAIVER OF CERTAIN CLAIMS; INDEMNITY BY TENANT

     14.01  Waiver of Certain Claims; Indemnity by Tenant. To the extent not
prohibited expressly by law, Tenant releases Landlord and its beneficiaries, if
any, and their agents, servants and employees, from and waives all claims for
damages to person or property sustained by Tenant or by any occupant of the
Premises or the Building, or by any other person, resulting directly or
indirectly from fire or other casualty, cause or any existing or future
condition, defect, matter or thing in or about the Premises, the Building or any
part of it, or from any equipment or appurtenance therein, or from any accident
in or about the Building, or from any act or neglect of any tenant or other
occupant of the Building or any part thereof or of any other person. This
Section shall apply especially, but not exclusively, to damage caused by water,
snow, frost, steam, excessive heat or cold, sewerage, gas, odors or noise, or
the bursting or leaking of pipes or plumbing fixtures, broken glass, sprinkling
or air conditioning devices or equipment, or flooding of basements, and shall
apply without distinction as to the person whose act or neglect was responsible
for the damage and whether the damage was due to any of the acts specifically
enumerated above, or from any other thing or circumstance, whether of a like
nature or of a wholly different nature. Subject to Section 21.01 nothing in this
Section or in Section 14.03 shall release Landlord from liability for its
negligence or the negligence of its agents and employees.

     14.02  Damage Caused by Tenant's Neglect.  If any damage to the Premises or
the Building or any equipment or appurtenance therein, whether belonging to
Landlord or to other tenants or occupants of the Building, results from any act
or neglect of Tenant, its employees, agents, contractors, licensees or invitees,
Tenant shall be liable therefor and if such damage is not repaired within thirty
(30) days after written notice from Landlord, Landlord may repair such damage at
its option and Tenant shall reimburse Landlord, upon demand by Landlord, for all
costs of such repairs and damages in excess of amounts, if any, paid to Landlord
under insurance covering such damage.

                                     -29-
<PAGE>
 
     14.03  Tenant Responsible for Personal Property.  All personal property
belonging to Tenant or any occupant of the Premises that is in the Building or
the Premises shall be there at the risk of Tenant or other person only and
Landlord shall not be liable for damage thereto or theft or misappropriation
thereof.

     14.04  Indemnification.

          (a)  To the extent not prohibited expressly by law, Tenant agrees to
hold Landlord and its beneficiaries, if any, and their officers, agents,
servants and employees, harmless and to indemnify each of them against claims
and liabilities, including reasonable attorneys' fees, for injuries to all
persons and damage to or theft or misappropriation or loss of property occurring
in or about the Premises arising from Tenant's occupancy of the Premises or the
conduct of its business or from any activity, work, or thing done, permitted or
suffered by Tenant in or about the Premises or from any breach or default on the
part of Tenant in the performance of any covenant or agreement on the part of
Tenant to be performed pursuant to the terms of this Lease or due to any other
act or omission of Tenant, its agents, contractors, invitees, licensees or
employees, but only to the extent of Landlord's liability, if any, in excess of
amounts, if any, paid to Landlord under insurance covering such claims or
liabilities.

          (b)  To the extent not prohibited expressly by law, Landlord agrees to
hold Tenant and its officers, agents, servants and employees, harmless and to
indemnify each of them against claims and liabilities, including reasonable
attorneys' fees, for injuries to all persons and damage to or theft or
misappropriation or loss of property occurring in or about the Premises arising
from the negligent acts of Landlord or its beneficiary or their employees,
agents or servants, or from any breach or default on the part of Landlord in the
performance of any covenant or agreement on the part of Landlord to be performed
pursuant to the terms of this Lease or due to any other act or omission of
Landlord or its beneficiaries or their agents, contractors, licensees or
employees, but only to the extent of Tenant's liability, if any, in excess of
amounts, if any, paid to Tenant under insurance covering such claims or
liabilities.


                                  ARTICLE 15.
                       DAMAGE OR DESTRUCTION BY CASUALTY

     15.01  Tenant's Obligation to Rebuild.  In the event of damage to, or
destruction of, any improvements on the Premises, or of the fixtures and
equipment therein, by fire or other casualty, Tenant shall promptly, at its
expense, repair, restore or rebuild to the extent possible to the same design,
plans and specifications as existed prior to the casualty. Rent shall not be
reduced or abated during the period of such repair, restoration or rebuilding
even if the improvements are not tenantable.

     15.02  Preconditions to Rebuilding.  Before Tenant commences such
repairing, restoration or rebuilding involving an estimated cost of more than
Fifty Thousand Dollars ($50,000.00), plans and specifications therefor, prepared
by a licensed architect satisfactory to Landlord shall be submitted to Landlord
for approval and Tenant shall furnish to Landlord (a)

                                     -30-
<PAGE>
 
an estimate of the cost of the proposed work, certified to by said architect;
(b) satisfactory evidence of sufficient contractor's comprehensive general
liability insurance covering Landlord, builder's risk insurance, and workmen's
compensation insurance; and (c) such other security as Landlord may require to
insure payment for the completion of all work free and clear of liens.
Landlord's approval of the plans and specifications shall not be unreasonably
withheld if such plans and specifications comply with the provisions of Section
15.01.

     15.03  Payment for Rebuilding.  All sums arising by reason of loss under
the insurance referred to in Section 21.02(c) shall be deposited with the
Depository pursuant to Section 15.06, and Tenant shall deposit with the
Depository any excess cost of the work over the amount held by the Depository as
proceeds of the insurance within thirty (30) days from the date of the
determination of the cost of the work by the architect in accordance with
Section 15.02. Tenant shall diligently pursue the repair or rebuilding of the
improvements in a good and workmanlike manner, using only high quality workmen
and materials. The Depository shall pay out construction funds from time to time
on the written direction of the architect, after making provision for a
reasonable holdback, for the purpose of completing such repair or rebuilding and
upon receipt of appropriate contractors' statements, with supporting affidavits
and lien waivers. Notwithstanding the foregoing, if the cost of the repair or
restoration is less than $50,000, all proceeds of insurance shall be paid to
Tenant in trust to be used for restoration and repair of such damage.

     15.04  Excess Insurance Proceeds.  Any excess of money received from
insurance remaining with the Depository after the repair or rebuilding of
improvements, if there is no default by Tenant in the performance of the
Tenant's covenants and agreements hereunder, shall be paid to Tenant; otherwise
said moneys shall be paid to Landlord. If this Lease shall be terminated
pursuant to Section 15.05, all insurance proceeds shall be paid to by Landlord.

     15.05  Failure to Rebuild.  If (i) Tenant shall not enter upon the repair
or rebuilding of the improvements within a period of ninety (90) days after the
insurance proceeds are made available by Landlord pursuant to Section 15.03 or
(ii) after commencement of such repair or rebuilding, Tenant does not prosecute
the same thereafter with such dispatch as may be necessary to complete the same
within a reasonable period after said damage or destruction occurs, and the
repair and rebuilding is not completed within one year from the date the
insurance proceeds are made available pursuant to Section 15.03, then, in
addition to whatever other remedies Landlord may have either under this Lease,
at law or in equity, Landlord may retain insurance proceeds, or the balance
thereof remaining in the hands of Landlord as security for the continued
performance and observance by Tenant of the Tenant's covenants and agreements
hereunder, or Landlord may terminate this Lease or Tenant's possession of the
Premises and then retain the amount so held as damages resulting from the
failure on the part of Tenant to comply with the provisions of this Article.

     15.06  Deposits.  All insurance proceeds, condemnation awards and amounts
deposited by Tenant ("Net Proceeds") shall be deposited with a bank or other
financial institution designated by the First Mortgagee, or if there is no First
Mortgagee, by Tenant (the "Depository"). Tenant may direct the investment of the
amounts so deposited with the Depository in the following:

                                     -31-
<PAGE>
 
          (a)  repurchase obligations of the Depository at all times fully
secured by direct and general obligations of the United States of America or
obligations guaranteed as to principal and interest by the United States of
America;

          (b)  direct and general obligations of the United States of America or
obligations guaranteed as to principal and interest by the United States of
America purchased at a price not more than par;

          (c)  certificates of deposit of the Depository at all times secured as
provided by applicable law; or

          (d) commercial paper which is rated "A-1" or better (or comparable
ratings) by Standard & Poor's Corporation or "P-1" or better (or comparable
ratings) by Moody's Investors Service, Inc., or the successors to such rating
organizations.

     Such investments of such funds shall mature in such amounts and on such
dates as to provide that amounts shall be available on the draw dates sufficient
to pay the amounts requested, and due to, Landlord or Tenant as the case may be.
The Depository shall not be liable for any loss resulting from the liquidation
of each and every such investment. The terms and conditions relating to such
deposit and investments shall otherwise be satisfactory to Landlord, Tenant and
the Depository. All interest or other earnings net of investment fees of the
Depository shall be added to and deemed to be part of Net Proceeds.


                                  ARTICLE 16.
                                EMINENT DOMAIN

     16.01  Whole Taking.  If the entire Building or a substantial part thereof
is taken or condemned by any competent authority for any public or quasi-public
use or purpose, the Term of this Lease shall end upon and not before the earlier
of the date when the possession of the part so taken is required for such use or
purpose or the effective date of the taking, and without apportionment of the
award to or for the benefit of Tenant. If any condemnation proceeding is
instituted in which it is sought to take or damage any part of the Building, the
taking of which, in Landlord's opinion, would prevent the economical operation
of the Building, or if the grade of any street or alley adjacent to the Building
is changed by any competent authority, and such taking, damage or change of
grade makes it necessary or desirable to remodel the Building to conform to the
taking, damage or changed grade, Landlord shall have the right to terminate this
Lease upon not less than ninety (90) days' notice prior to the date of
termination designated in the notice. In either of these events, Rent at the
then current rate shall be apportioned as of the date of the termination. No
money or other consideration shall be payable by Landlord to Tenant for the
right of termination, and Tenant shall have no right to share in the
condemnation award, whether for a total or partial taking, for loss of Tenant's
leasehold or improvements or other loss or expenses or in any judgment for
damages caused by the change of grade. Tenant may however file a separate claim
for Allocation expenses and for any of Tenant's personal property taken,
provided such claim does not reduce Landlord's award.

                                     -32-
<PAGE>
 
     16.02  Partial Taking.  If only a part of the Premises shall be so taken or
condemned, and as a result thereof the balance of the Premises can be used for
the same purpose as prior to such taking, this Lease shall not terminate and
Tenant, at its sole cost and expense, shall repair and restore the Premises and
all improvements thereon to the extent of the condemnation award. Tenant shall
promptly and diligently proceed to make a complete architectural unit of the
remainder of the improvements first complying with the procedure set forth in
Section 15.02. The amount of the award relating to the improvements and shall be
held and disbursed in accordance with the procedure set forth in Sections 15.03
and 15.06. If Tenant does not make a complete architectural unit of the
remainder of the improvements within a reasonable period after such taking or
condemnation, not to exceed three hundred sixty five (365) days, then, in
addition to whatever other remedies Landlord may have either under this Lease,
at law or in equity, Landlord may receive the entire award or the balance
thereof remaining in the custody of the Depository, as the case may be, as
liquidated damages resulting from the failure of Tenant to comply with the
provisions of this Section. Any portion of such award as may not have to be
expended for such repairing or restoration shall be paid to Landlord. There
shall be no abatement or reduction in any rental because of such taking or
condemnation unless a portion of the Building is taken in which event Base Rent
shall abate based on the percentage of the rentable space in the Building so
taken and not replaced pursuant to this Section.


                                  ARTICLE 17.
                                    DEFAULT

     17.01  Events of Default. The occurrence of any one or more of the
following matters constitutes a Default by Tenant under this Lease:

          (a)  Failure by Tenant to pay any Rent when due if such failure
continues for ten (10) days after notice from Landlord of such failure;

          (b)  Failure by Tenant to pay when due any other monies required to be
paid by Tenant under this Lease if such failure continues for ten (10) days
after notice from Landlord of such failure;

          (c)  Failure by Tenant to cure, immediately after receipt of notice
from Landlord, any hazardous condition which Tenant has created in violation of
law or of this Lease;

          (d)  Failure by Tenant to observe or to perform any other covenant,
agreement, condition or provision of this Lease, if such failure continues for
thirty (30) days after notice thereof from Landlord to Tenant;

          (e)  The levy upon, under writ of execution or the attachment by legal
process of, the leasehold interest of Tenant, or the filing or creation of a
lien with respect to such leasehold interest, which lien shall not be released
or discharged within ten (10) days from the date of such filing;

                                     -33-

<PAGE>
 
            (f)  Tenant vacates or abandons the Premises or fails to take
possession of the Premises when available for occupancy (the transfer of a
substantial part of the operations, business and personnel of Tenant to some
other location being deemed, without limiting the meaning of the term, "vacates
or abandons," to be a vacation or abandonment within the meaning of this clause
(h) unless Tenant posts a full-time security guard at the Premises), whether or
not Tenant thereafter continues to pay Rent due under this Lease;

            (g)  Tenant becomes insolvent or bankrupt or admits in writing its
inability to pay its debts as they mature, or makes an assignment for the
benefit of creditors, or applies for or consents to the appointment of a trustee
or receiver for Tenant or for the major part of its property;

            (h)  A trustee or receiver is appointed for Tenant or for the major
part of its property and is not discharged within sixty (60) days after such
appointment;

            (i)  Any bankruptcy, reorganization, arrangement, insolvency or
liquidation proceedings, or other proceedings for relief under any bankruptcy
law, or similar law for the relief of debtors, are instituted (i) by Tenant or
(ii) against Tenant and are allowed against it or are consented to by it or are
not dismissed within sixty (60) days after such institution;

            (j)  The aggregate number of days of Tenant Delay shall exceed
thirty (30); or

            (k)  A Default occurs under the 1501 Lease.

     17.02  Rights and Remedies of Landlord. If a Default occurs, Landlord shall
have the rights and remedies hereinafter set forth, which shall be distinct,
separate and cumulative and which shall not operate to exclude or deprive
Landlord of any other right or remedy allowed it by law:

            (a)  Landlord may terminate this Lease by giving to Tenant notice of
Landlord's election to do so, in which event the Term of this Lease shall end,
and all rights, title and interest of Tenant hereunder shall expire, on the date
stated in such notice;

            (b)  Landlord may terminate the right of Tenant to possession of the
Premises without terminating this Lease by giving notice to Tenant that Tenant's
right of possession shall end on the date stated in such notice, whereupon the
right of Tenant to possession of the Premises or any part thereof shall cease on
the date stated in such notice; and

            (c)  Landlord may enforce the provisions of this Lease and may
enforce and protect the rights of Landlord hereunder by a suit or suits in
equity or at law for the specific performance of any covenant or agreement
contained herein, or for the enforcement of any other appropriate legal or
equitable remedy, including recovery of all moneys due or to become due from
Tenant under any of the provisions of this Lease.

                                      -34-
<PAGE>
 
     17.03  Right to Re-Enter.  If Landlord exercises either of the remedies
provided for in Sections 17.02(a) or (b), Tenant shall surrender possession and
vacate the Premises and shall deliver immediately possession thereof to
Landlord, and Landlord may re-enter and take complete and peaceful possession of
the Premises, with process of law, full and complete license to do so being
hereby granted to Landlord, and Landlord may remove all occupants and property
therefrom, using such force as may be necessary, without being deemed guilty in
any manner of trespass, eviction or forcible entry and detainer and without
relinquishing Landlord's right to rent or any other right given to Landlord
hereunder or by operation of law.

     17.04  Current Damages.  If Landlord terminates the right of Tenant to
possession of the Premises without terminating this Lease, Landlord shall have
the right to immediate recovery of all amounts then due hereunder. Such
termination of possession shall not release Tenant, in whole or in part, from
Tenant's obligation to pay the Rent hereunder for the full Term, and Landlord
shall have the right, from time to time, to recover from Tenant, and Tenant
shall remain liable for, all Base Rent, Rent Adjustments and any other sums
accruing as they become due under this Lease during the period from the date of
such notice of termination of possession to the stated end of the Term. In any
such case, Landlord shall use diligent efforts to mitigate its damages and to
relet the Premises or any part thereof for the account of Tenant for such rent,
for such time (which may be for a term extending beyond the Term of this Lease)
and upon such terms as Landlord shall determine and collect the rents from such
reletting. Landlord shall not be required to accept any tenant offered by Tenant
or to observe any instructions given by Tenant relative to such reletting. Also,
in any such case, Landlord may make repairs, alterations and additions in or to
the Premises and redecorate the same to the extent reasonably deemed by Landlord
necessary or desirable and in connection therewith change the locks to the
Premises, and Tenant shall pay upon demand the cost of all the foregoing
together with Landlord's expenses of reletting. The rents from any such
reletting shall be applied first to the payment of the expenses of reentry,
redecoration, repair and alterations and the expenses of reletting and second to
the payment of Rent herein provided to be paid by Tenant. Any excess or residue
shall operate only as an offsetting credit against the amount of Rent due and
owing as the same thereafter becomes due and payable hereunder, and the use of
such offsetting credit to reduce the amount of Rent due Landlord, if any, shall
not be deemed to give Tenant any right, title or interest in or to such excess
or residue and any such excess or residue shall belong to Landlord solely, and
in no event shall Tenant be entitled to a credit on its indebtedness to Landlord
in excess of the aggregate sum, including Base Rent and Rent Adjustments, which
would have been paid by Tenant for the period for which the credit to Tenant is
being determined, had no Default occurred. No such reentry or repossession,
repairs, alterations and additions, or reletting shall be construed as an
eviction or ouster of Tenant or as an election on Landlord's part to terminate
this Lease, unless a written notice of such intention is given to Tenant, or
shall operate to release Tenant in whole or in part from any of Tenant's
obligations hereunder, and Landlord, at any time and from time to time, may sue
and recover judgment for any deficiencies from time to time remaining after the
application from time to time of the proceeds of any such reletting.

     17.05  Final Damages.  If this Lease is terminated by Landlord as provided
in Section 17.02(a), Landlord shall be entitled to recover from Tenant all Rent
accrued and unpaid for the period up to and including such termination date, as
well as all other additional sums payable


                                     -35-
<PAGE>
 
by Tenant, or for which Tenant is liable or in respect of which Tenant has
agreed to indemnify Landlord under any of the provisions of this Lease, which
may be then owing and unpaid, and all reasonable costs and expenses, including
court costs and attorneys' fees incurred by Landlord in the enforcement of its
rights and remedies hereunder, and, in addition, Landlord shall be entitled to
recover as damages for loss of the bargain and not as a penalty the aggregate
sum which at the time of such termination represents the excess, if any, of the
present value of the aggregate rents which would have been payable after the
termination date had this Lease not been terminated, including, without
limitation, Base Rent at the annual rate or respective annual rates for the
remainder of the Term provided for in Article 2 of this Lease or elsewhere
herein and the amount projected by Landlord to represent Rent Adjustments for
the remainder of the Term pursuant to Article 3 of this Lease, over the then
present value of the then aggregate fair rental value of the Premises for the
balance of the Term, such present worth to be computed in each case on the basis
of a five percent (5%) per annum discount from the respective dates upon which
such rentals would have been payable hereunder had this Lease not been
terminated, and (c) any damages in addition thereto, including reasonable
attorneys' fees and court costs, which Landlord has sustained as a result of the
breach of any of the covenants of this Lease other than for the payment of Rent.

     17.06  Removal of Personal Property.  All property of Tenant removed from
the Premises by Landlord pursuant to any provisions of this Lease or of law may
be handled, removed or stored by Landlord at the cost and expense of Tenant, and
Landlord in no event shall be responsible for the value, preservation or
safekeeping thereof. Tenant shall pay Landlord for all expenses incurred by
Landlord in such removal and storage charges against such property as long as
the same is in Landlord's possession or under Landlord's control. All such
property not removed from the Premises or retaken from storage by Tenant within
thirty (30) days after the end of the Term, however terminated, at Landlord's
option, shall be conclusively deemed to have been conveyed by Tenant to Landlord
as by bill of sale without further payment or credit by Landlord to Tenant.

     17.07  Attorneys' Fees.  Tenant shall pay all of Landlord's costs, charges
and expenses, including court costs and attorneys' fees, incurred in
successfully enforcing Tenant's obligations under this Lease, incurred by
Landlord in any action brought by Tenant in which Landlord is the prevailing
party, or incurred by Landlord in any litigation, negotiation or transaction in
which Tenant causes Landlord, without Landlord's fault, to become involved or
concerned. Landlord shall pay all of Tenant's costs, charges and expenses,
including court costs and attorneys' fees, incurred in successfully enforcing
Landlord's obligations under this Lease, incurred by Tenant in any action
brought by Landlord in which Tenant is the prevailing party, or incurred by
Tenant in any litigation, negotiation or transaction in which Landlord causes
Tenant without Tenant's fault, to become involved or concerned.

     17.08  Assumption or Rejection in Bankruptcy.  If Tenant is adjudged
bankrupt, or a trustee in bankruptcy is appointed for Tenant, Landlord and
Tenant, to the extent permitted by law, agree to request that the trustee in
bankruptcy determine within sixty (60) days thereafter whether to assume or to
reject this Lease.

                                     -36-
<PAGE>
 
                                  ARTICLE 18.
                                 SUBORDINATION

     18.01  Subordination.  Landlord intends to execute and deliver and may
execute and deliver hereafter from time to time a first mortgage or first trust
deed in the nature of a mortgage, both being hereinafter referred to as a "First
Mortgage," against the Land and Building or any interest therein. If requested
by the mortgagee or trustee under any First Mortgagee, Tenant will either (a)
subordinate its interest in this Lease to said First Mortgage, and to any and
all advances made thereunder and to the interest thereon, and to all renewals,
replacements, supplements, amendments, modifications and extensions thereof, or
(b) make certain of Tenant's rights and interest in this Lease superior thereto;
and Tenant will execute and deliver such agreement or agreements promptly, as
may be reasonably required by such First Mortgagee; provided that, as a
condition to subordinating its rights and interests under this Lease to any
mortgage or trust deed, Tenant shall be entitled to require the First Mortgagee
to enter into a non-disturbance and attornment agreement with Tenant, which
agreement shall be in said holder's standard form not inconsistent with this
Lease. Tenant covenants it will not subordinate this Lease to any mortgage or
trust deed other than a First Mortgage without the prior written consent of the
First Mortgagee.

     18.02  Liability of Holder of First Mortgage; Attornment. It is further
agreed that (a) if any First Mortgage shall be foreclosed, (i) the holder of the
First Mortgagee, or purchaser at any foreclosure sale (or grantee in a deed in
lieu of foreclosure), as the case may be, shall not be (x) liable for any act or
omission of any prior landlord (including Landlord), (y) subject to any offsets
or counterclaims which Tenant may have against a prior landlord (including
Landlord), or (z) bound by any prepayment of Base Rent or Rent Adjustments which
Tenant may have made in excess of the amounts then due for the next succeeding
month, (ii) the liability of the First Mortgagee or purchaser at such
foreclosure sale or the liability of a subsequent owner designated as Landlord
under this Lease shall exist only so long as such trustee, mortgagee, purchaser
or owner is the owner of the Building or Land and such liability shall not
continue or survive after further transfer of ownership; and (iii) upon request
of the First Mortgagee, if the First Mortgage is foreclosed, Tenant will attorn,
as Tenant under this Lease, to the purchaser at any foreclosure sale under any
First Mortgage, and Tenant will execute such instruments as may be necessary or
appropriate to evidence such attornment; and (b) this Lease may not be modified
or amended so as to reduce Rent or shorten the Term provided hereunder, or so as
to affect adversely in any other respect to any material extent the rights of
Landlord, and this Lease shall not be cancelled or surrendered, without the
prior written consent, in each instance, of the First Mortgagee.

     18.03  Modification Required by First Mortgagee.  Should any prospective
First Mortgagee require a modification or modifications of this Lease, which
modification or modifications will not cause an increased cost or expense to
Tenant or in any other way materially change the rights and obligations of
Tenant hereunder, Tenant agrees that this Lease may be so modified and agrees to
execute whatever documents are required therefor and deliver the same to
Landlord within ten (10) days following the request therefor.

                                     -37-
<PAGE>
 
     18.04  Short Form Lease.  Should any prospective First Mortgagee require
execution of a short form of lease for recording (containing the names of the
parties, a description of the Premises, and the term of this Lease) or a
certification from Tenant concerning this Lease in such form as may be required
by a prospective mortgagee, Tenant agrees to promptly execute such short form of
lease or certificate and deliver the same to Landlord within ten (10) days
following the request therefor.


                                  ARTICLE 19.
                             MORTGAGEE PROTECTION

     Tenant agrees to give any First Mortgagee, by registered or certified mail,
a copy of any notice or claim of default served upon Landlord by Tenant,
provided that prior to such notice, Tenant has been notified in writing, by way
of service on Tenant of a copy of an assignment of Landlord's interests in
leases, or otherwise, of the address of such First Mortgagee. Tenant further
agrees that if Landlord has failed to cure such default within twenty (20) days
after such notice to Landlord (or if such default cannot be cured or corrected
within that time, then such additional time as may be necessary if Landlord has
commenced within such twenty (20) days and is pursuing diligently the remedies
or steps necessary to cure or correct such default), then the First Mortgagee
shall have an additional thirty (30) days within which to cure or correct such
default (or if such default cannot be cured or corrected within that time, then
such additional time as may be necessary if such First Mortgagee has commenced
within such thirty (30) days and is pursuing diligently the remedies or steps
necessary to cure or correct such default, including the time necessary to
obtain possession if possession is necessary to cure or correct such default).


                                  ARTICLE 20.
                             ESTOPPEL CERTIFICATE
 
     Upon execution of this Lease by Landlord and Tenant, Tenant shall
simultaneously execute and deliver a copy of the Estoppel Certificate attached
hereto as Rider D. Tenant agrees that from time to time upon not less than ten
(10) days' prior request by Landlord, or any First Mortgagee or any ground
lessor, Tenant (or any permitted assignee, subtenant, licensee, concessionaire
or other occupant of the Premises claiming by, through or under Tenant) will
deliver to Landlord or to any First Mortgagee or ground lessor, a statement in
writing signed by Tenant certifying (a) that this Lease is unmodified and in
full force and effect (or if there have been modifications, that this Lease as
modified is in full force and effect and identifying the modifications); (b) the
date upon which Tenant began paying Rent and the dates to which Rent and other
charges have been paid; (c) that Landlord is not in default under any provision
of this Lease, or, if in default, the nature thereof in detail; (d) that the
Premises have been completed in accordance with the terms hereof and Tenant is
in occupancy and paying Rent on a current basis with no rental offsets or claims
or if not state the exceptions to the items not completed in accordance with the
Final Plans; (e) that there has been no prepayment of Rent other than that
provided for in this Lease; (f) that there are no actions, whether voluntary or

                                     -38-
<PAGE>
 
otherwise, pending against Tenant under the bankruptcy laws of the United States
or any State thereof; and (g) such other matters as may be reasonably required
and not inconsistent with the terms of this Lease by Landlord, the First
Mortgagee or ground lessor.


                                  ARTICLE 21.
                           SUBROGATION AND INSURANCE

     21.01  Waiver of Subrogation.  Landlord and Tenant agree to have all "all-
risk" coverage and other property damage insurance and any rent loss or business
interruption insurance which may be carried by either of them endorsed with a
clause providing that any release from liability of or waiver of claim for
recovery from the other party entered into in writing by the insured thereunder
prior to any loss or damage shall not affect the validity of said policy or the
right of the insured to recover thereunder and providing further that the
insurer waives all rights of subrogation which such insurer might have against
the other party. Without limiting any release or waiver of liability or recovery
set forth elsewhere in this Lease, and notwithstanding anything in this Lease
which may appear to be to the contrary, each of the parties hereto waives all
claims for recovery from the other party for any loss or damage to any of its
property insured under valid and collectible insurance policies to the extent of
any recovery collectible under such insurance policies. Notwithstanding the
foregoing or anything contained in this Lease to the contrary, any release or
any waiver of claims shall not be operative, and the foregoing endorsements
shall not be required, in any case where the effect of such release or waiver is
to invalidate insurance coverage or invalidate the right of the insured to
recover thereunder or increase the cost thereof (provided that in the case of
increased cost the other party shall have the right, within ten (10) days
following written notice, to pay such increased cost keeping such release or
waiver in full force and effect).

     21.02  Tenant's Insurance.  Tenant shall carry insurance during the entire
Term hereof with terms, coverages and in companies satisfactory to Landlord and
with such increases in limits as Landlord may request from time to time, but
initially Tenant shall maintain the following coverages in the following
amounts:

          (a)  Comprehensive or commercial general liability insurance,
     including contractual liability, on an occurrence basis, in an amount not
     less than Fifteen Million Dollars ($15,000,000.00) combined single limit
     per occurrence, covering Tenant, Landlord and its beneficiaries as a named
     insured and Landlord's mortgagee as an additional insured.

          (b)  Insurance against fire, sprinkler leakage, vandalism and the
     extended coverage perils for the full replacement cost of all additions,
     improvements and alterations to the Premises owned or made by Tenant, if
     any, and of all office furniture, trade fixtures, office equipment,
     merchandise and all other items of Tenant's property on the Premises, with
     loss or damage payable to Landlord and Tenant as their interests may
     appear.

                                     -39-
<PAGE>
 
          (c)  Standard Fire and Extended Coverage Policy and all other risks of
     direct physical loss as insured against under Special Extended Coverage
Endorsement, insuring the improvements at any time situated upon the Premises
against loss or damage by fire, lightning, wind storm, hail storm, aircraft,
vehicles, smoke, explosion, riot or civil commotion. The insurance coverage
shall be for not less than 100% of the full replacement cost of such improvement
with all proceeds of insurance payable to Landlord. Landlord shall be a named
insured on such policies. The insurance shall include standard mortgagee loss
payable clauses for benefit of Landlord's Mortgagee. The full replacement cost
of improvements shall be determined every five (5) years by an insurance
appraiser selected by Tenant with Landlord's reasonable approval and paid for by
Tenant or by other means reasonably acceptable to Landlord and its First
Mortgagee. Any insurance appraiser hired by Tenant shall submit a written report
of his appraisal to Landlord and Tenant and if said report shows that the
improvements are not insured as herein required, Tenant shall promptly obtain
such additional insurance as is required;

          (d)  Boiler Insurance, insuring Landlord and Tenant with the same
     limits of coverage as provided in subsection (c) for loss or damage by
     boiler or internal explosion or break down of boilers;

          (e)  Worker's Compensation Insurance, insuring Tenant from all
     worker's compensation claims;

          (f)  Plate Glass Insurance, insuring Landlord and Tenant from damage
     to any plate glass on the Premises; and

          (g)  Builders Risk Insurance insuring Landlord and Tenant against "all
     risks" including collapse and transit coverage during any construction of
     any improvements to or repair of the Premises after the Commencement Date
     covering the total value of work performed and equipment, supplies and
     material furnished.

          Such insurance shall be written by companies of nationally recognized
     financial standing, legally qualified to issue such insurance and accorded
     a rating by A.M. Best Company, Inc. of A:XII or higher at the time of
     issuance of any such policy. Each insurance policy carried by Tenant shall
     contain, where appropriate, a clause stating that such policy will be
     considered as primary insurance for Landlord and its agents and
     beneficiaries and not call into contribution any other insurance that may
     be available to Landlord. All insurance claims other than under Worker's
     Compensation and contents insurance pertaining to the Premises in amounts
     of $25,000 or less shall be adjusted by the insurer with Tenant, and all
     claims in excess of $25,000 shall be adjusted by Landlord and Tenant
     jointly.

     21.03  Certificates of Insurance.  Tenant shall furnish to Landlord, prior
to the commencement of the Term and at least thirty (30) days prior to the
expiration of such policies, policies or certificates evidencing such coverage,
which policies or certificates shall state that such insurance coverage may not
be reduced, cancelled or not renewed without at least thirty

                                     -40-
<PAGE>
 
(30) days' prior written notice to Landlord and Tenant (unless such cancellation
is due to nonpayment of premium, and in that case, only ten (10) days' prior
written notice shall be sufficient).

     21.04  Compliance with Requirements.  Tenant shall comply with all
applicable laws and ordinances, all orders and decrees of court and all
requirements of other governmental authorities, and shall not make any use of
the Premises, directly or indirectly, which may be prohibited thereby, which may
be dangerous to person or property, which may jeopardize any insurance coverage,
or which may increase the cost of insurance or require additional insurance
coverage.


                                  ARTICLE 22.
                                   NONWAIVER

     No waiver of any condition expressed in this Lease shall be implied by any
neglect of Landlord to enforce any remedy on account of the violation of such
condition whether or not such violation is continued or repeated subsequently,
and no express waiver shall affect any condition other than the one specified in
such waiver and that one only for the time and in the manner specifically
stated. Without limiting Landlord's rights under Article 9, it is agreed that no
receipt of moneys by Landlord from Tenant after the termination in any way of
the Term or of Tenant's right of possession hereunder or after the giving of any
notice shall reinstate, continue or extend the Term or affect any notice given
to Tenant prior to the receipt of such moneys. It is also agreed that after the
service of notice or the commencement of a suit or after final judgment for
possession of the Premises, Landlord may receive and collect any moneys due, and
the payment of said moneys shall not waive or affect said notice, suit or
judgment.


                                  ARTICLE 23.
                              TENANT'S AUTHORITY

     Tenant (a) represents and warrants that this Lease has been duly
authorized, executed and delivered by and on behalf of Tenant and constitutes
the valid and binding agreement of Tenant in accordance with the terms hereof,
(b) if Landlord so requests, it shall deliver to Landlord or its agent,
concurrently with the delivery of this Lease executed by Tenant, certified
resolutions of the board of directors (and shareholders, if required)
authorizing Tenant's execution and delivery of this Lease and the performance of
Tenant's obligations hereunder, and (c) until Landlord is notified in writing of
a substitute therefor, Tenant's Authorized Representative set forth in the
Schedule shall have full power and authority to take action on behalf of and to
bind Tenant with respect to all matters relating to this Lease and the Premises.

                                     -41-
<PAGE>
 
                                 ARTICLE 24. 
                              REAL ESTATE BROKERS

     Landlord and Tenant each represent that it has not dealt with a broker in
connection with this Lease and agrees to indemnify and hold the other harmless
from all damages, liability and expense, including reasonable attorneys' fees,
arising from any claims or demands of any broker or brokers or finders for any
commission alleged to be due such broker or brokers or finders in connection
with its having introduced Landlord and Tenant or having participated in the
negotiation of this Lease.


                                  ARTICLE 25.
                                    NOTICES

     All notices and demands required or desired to be given by either party to
the other with respect to this Lease or the Premises shall be in writing and
shall be delivered personally, sent by overnight courier service, prepaid, or
sent by United States registered or certified mail, return receipt requested,
postage prepaid, and addressed as herein provided. Notices to or demands upon
Tenant shall be addressed to Tenant at the address set forth in the Schedule
prior to its occupancy of the Premises and at the Premises following its
occupancy of the Premises. Notices to or demands upon Landlord shall be
addressed to Landlord c/o RERC Capital Market Group, L.L.C., at 2 N. LaSalle
Street, Suite 730, Chicago, Illinois 60601, Attn: Joseph Beale. Notices and
demands shall be deemed given and served (a) upon receipt or refusal, if
delivered personally, (b) one (1) business day after deposit with an overnight
courier service or (c) three (3) business days after deposit in the United
States mails, if mailed. Either party may change its address for receipt of
notices by giving notice of such change to the other party in accordance
herewith. Notices and demands from Landlord to Tenant may be signed by Landlord,
its beneficiaries, the managing agent for the Real Property or the agent of any
of them.


                                  ARTICLE 26.
                              HAZARDOUS MATERIALS

     26.01  Defined Terms.

          (a)  "Claim" shall mean and include any demand, cause of action,
proceeding, or suit for any one or more of the following: (i) actual or punitive
damages, losses, injuries to person or property, damages to natural resources,
fines, penalties, interest, contribution or settlement, (ii) the costs and
expenses of site investigations, feasibility studies, information requests,
health or risk assessments, or Response (as hereinafter defined) actions, and
(iii) the costs and expenses of enforcing insurance, contribution or
indemnification agreements.

          (b)  "Environmental Laws" shall mean and include all federal, state
and local statutes, ordinances, regulations and rules in effect and as amended
from time to time relating to environmental quality, health, safety,
contamination and cleanup, including, without limitation, the Clean Air Act, 42
U.S.C. Section 7401 et seq.; the Clean Water Act, 33 U.S.C. Section 1251 et
seq., and the Water Quality Act of 1987; the Federal Insecticide, Fungicide, and


                                     -42-
<PAGE>
 
Rodenticide Act ("FIFRA"), 7 U.S.C. Section 136 et seq.; the Marine Protection,
Research, and Sanctuaries Act, 33 U.S.C. Section 1401 et seq.; the National
Environmental Policy Act, 42 U.S.C. Section 4321 et seq.; the Noise Control Act,
42 U.S.C. Section 4901 et seq.; the Occupational Safety and Health Act, 29
U.S.C. Section 651 et seq.; the Resource Conservation and Recovery Act ("RCRA"),
42 U.S.C. Section 6901 et seq., as amended by the Hazardous and Solid Waste
Amendments of 1984; the Safe Drinking Water Act, 42 U.S.C. Section 300f et seq.;
the Comprehensive Environmental Response, Compensation and Liability Act
("CERCLA"), 42 U.S.C. Section 9601 et seq., as amended by the Superfund
Amendments and Reauthorization Act, the Emergency Planning and Community Right-
to-Know Act, and the Radon Gas and Indoor Air Quality Research Act; the Toxic
Substances Control Act ("TSCA"), 15 U.S.C. Section 2601 et seq.; the Atomic
Energy Act, 42 U.S.C. Section 2011 et seq., and the Nuclear Waste Policy Act of
1982, 42 U.S.C. Section 10101 et seq.; and the Environmental Protection Act of
Illinois ("IEPA"), Ill. Rev. Stat. ch. 111 1/2, para. 1001 et seq., and state
and local superlien and environmental statutes and ordinances, with implementing
regulations, rules and guidelines, as any of the foregoing may be amended from
time to time. Environmental Laws shall also include all state, regional, county,
municipal, and other local laws, regulations, and ordinances insofar as they are
equivalent or similar to the federal laws recited above or purport to regulate
Hazardous Materials (as hereinafter defined).

          (c)  "Hazardous Materials" shall mean and include the following,
including mixtures thereof: any hazardous substance, pollutant, contaminant,
waste, by-product or constituent regulated under CERCLA; oil and petroleum
products and natural gas, natural gas liquids, liquefied natural gas and
synthetic gas usable for fuel; pesticides regulated under FIFRA; asbestos and
asbestos-containing materials, PCBs, and other substances regulated under TSCA;
source material, special nuclear material, by-product material and any other
radioactive materials or radioactive wastes, however produced, regulated under
the Atomic Energy Act or the Nuclear Waste Policy Act; chemicals subject to the
OSHA Hazard Communication Standard, 29 C.F.R. (S) 1910.1200 et seq.; and
industrial process and pollution control wastes whether or not hazardous within
the meaning of RCRA, and any other hazardous substance, pollutant or contaminant
regulated under any other Environmental Law.

          (d)  "Manage" or "Management" means to generate, manufacture, process,
treat, store, use, re-use, refine, recycle, reclaim, blend or burn for energy
recovery, incinerate, accumulate speculatively, transport, transfer, dispose of
or abandon Hazardous Materials.

          (e)  "Release" or "Released" shall mean any actual or threatened
spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting,
escaping, leaching, dumping or disposing of Hazardous Materials into the
environment, as "environment" is defined in CERCLA.

          (f)  "Response" or "Respond" shall mean action taken to correct,
remove, remediate, clean up, prevent, mitigate, monitor, evaluate, investigate,
assess or abate the Release of a Hazardous Material.

     26.02  Tenant's Obligations with Respect to Environmental Matters. During
the term of this Lease, (i) Tenant shall comply at its sole cost and expense
with all Environmental Laws; (ii) Tenant shall not Manage, or authorize the
Management of, any Hazardous Materials on the


                                      -43-
<PAGE>
 
Building or Land, including installation of any underground storage tanks,
without prior written disclosure to and prior written approval by Landlord;
(iii) Tenant shall not take any action that would subject the Building or Land
to the permit requirements under RCRA for storage, treatment or disposal of
Hazardous Materials; (iv) Tenant shall not dispose of Hazardous Materials in
dumpsters; (v) Tenant shall not discharge Hazardous Materials into drains or
sewers on the Real Property; (vi) Tenant shall not cause or allow the Release of
any Hazardous Materials on, to or from the the Real Property and (vii) Tenant
shall arrange at its sole cost and expense for the lawful transportation and 
off-site disposal at permitted landfills or other permitted disposal facilities
and otherwise in accordance with all applicable Environmental Laws, of all
Hazardous Materials that it generates.

     26.03  Copies of Notices.  During the Term of this Lease, Tenant shall
provide Landlord promptly with copies of all summons, citations, directives,
information inquiries or requests, notices of potential responsibility, notices
of violation or deficiency, orders or decrees, Claims, complaints,
investigations, judgments, letters, notices of environmental liens or Response
actions in progress, and other communications, written or oral, actual or
threatened, from the United States Environmental Protection Agency, Occupational
Safety and Health Administration, Illinois Environmental Protection Agency, or
other federal, state, or local agency or authority, or any other entity or
individual, concerning (i) any actual or alleged Release of a Hazardous Material
on, to or from the Premises; (ii) the imposition of any lien on the Premises;
(iii) any actual or alleged violation of, or responsibility under, any
Environmental Laws; or (iv) any actual or alleged liability under any theory of
common law tort or toxic tort, including without limitation, negligence,
trespass, nuisance, strict liability, or ultrahazardous activity.

     26.04  Landlord's Right to Inspect.  Landlord and Landlord's employees
shall have the right to enter the Premises and conduct appropriate inspections
or tests for the purpose of (i) determining Tenant's compliance with
Environmental Laws, and (ii) determining the type, kind and quantity of all
products, materials and substances brought onto the Premises, or made or
produced thereon. Landlord and its agents and representatives shall have the
right to take samples in quantities sufficient for analysis of all products,
materials and substances present on the Premises including, but not limited to,
samples, products, materials or substances brought onto or made or produced on
the Premises by Tenant or its agents, employees, contractors or invitees. Tenant
agrees to cooperate with such investigations by providing any relevant
information requested by Landlord, including, but not limited to, information
Landlord requests to comply with the Illinois Responsible Property Transfer Act,
Ill. Rev. Stat. ch. 30, para. 901 et seq. (1989), 765 ILCS 90/1 et seq. (1992).
Tenant may not perform any sampling, testing, or drilling to locate Hazardous
Materials in the Building components on the Premises without the Landlord's
prior written consent.

     26.05  Tests and Reports.  Within ten (10) days of Tenant's receipt of a
written request by Landlord, Tenant shall provide Landlord with (i) copies of
all environmental reports and tests obtained by Tenant; (ii) copies of
transportation and disposal contracts (and related manifests, schedules,
reports, and other information) entered into or obtained by Tenant with respect
to any Hazardous Materials; (iii) copies of any permits issued to Tenant under
Environmental Laws with respect to the Premises; (iv) copies of any and all
reports, notifications, and other filings made by Tenant to any federal, state,
or local environmental authorities or agencies; and (v) any other applicable
documents and information with respect to environmental matters relating to the


                                     -44-
<PAGE>
 
premises. Tenant shall provide Landlord with the results of appropriate reports
and tests, with transportation and disposal contracts for Hazardous Materials,
with any permits issued under Environmental Laws, and with any other documents
necessary to demonstrate that Tenant complies with all Environmental Laws
relating to the Premises.

     26.06  Tenant's Obligation to Respond.  If Tenant's Management of Hazardous
Materials at the Premises (i) gives rise to liability or to a Claim under any
Environmental Law, or any common law theory of tort or otherwise; (ii) causes a
threat to, or endangers, the public health; or (iii) creates a nuisance or
trespass, Tenant shall, at its sole cost and expense, promptly take all
applicable action in response so as to comply with all applicable Environmental
Laws and eliminate or avoid any liability claim with respect thereto.

     26.07  Landlord's Right to Act.  In the event that Tenant shall fail to
comply with any of its obligations under this Article 26 as and when required
hereunder, Landlord shall have the right (but not the obligation) to take such
action as is required to be taken by Tenant hereunder and in such event, Tenant
shall be liable and responsible to Landlord for all costs, expenses,
liabilities, claims and other obligations paid, suffered, or incurred by
landlord in connection with such matters. Tenant shall reimburse Landlord
immediately upon demand for all such amounts for which Tenant is liable.

     26.08  Indemnification.  Notwithstanding anything contained in this Lease
to the contrary, Tenant shall reimburse, defend, indemnify and hold Landlord,
and its beneficiaries, officers, directors, shareholders, employees, and agents,
free and harmless from and against any and all Claims, Response costs, losses,
liabilities, damages, costs, and expenses, including, without limitation, loss
of rental income, loss due to business interruption, and reasonable attorneys'
fees and costs (collectively "Environmental Claims"), arising out of or in any
way connected with any or all of the following:

               (i)    any Hazardous Materials which, at any time during the
          Term, are or were actually or allegedly Managed, generated, stored,
          treated, released, disposed of or otherwise located on or at the
          Building or Land (regardless of the location at which such Hazardous
          Material are now or may in the future be located or disposed of),
          including but not limited to, any and all (1) liabilities under any
          common law theory of tort, nuisance, strict liability, ultrahazardous
          activity, negligence or otherwise based upon, resulting from or in
          connection with any Hazardous Material; (2) obligations to take
          Response, cleanup or corrective action pursuant to any investigation
          or remediation in connection with the decontamination, removal,
          transportation, incineration, or disposal of any of the foregoing; and

               (ii)   any actual or alleged illness, disability, injury, or
          death of any person; in any manner arising out of or allegedly arisen
          out of exposure to Hazardous Materials or other substances or
          conditions present at the Building or Land, regardless of when any
          such illness, disability, injury, or death shall have occurred or been
          incurred or manifested itself; and


                                     -45-
<PAGE>
 
               (iii)  any actual or alleged failure of Tenant or the Building
     or Land at any time and from time to time to comply with all applicable
     Environmental Laws, whether before or after the effective date of this
     Lease; and

               (iv) any failure by Tenant to comply with its obligations under
     this Article 26.

     In the event any Claims or other assertion of liability shall be made
against Landlord for which Landlord is entitled to indemnity hereunder, Landlord
shall notify Tenant of such Claim or assertion of liability and thereupon Tenant
shall, at its sole cost and expense, assume the defense of such Claim or
assertion of liability and continue such defense at all times thereafter until
completion. The obligations of Tenant under this Article 26 shall survive any
termination or expiration of this Lease. Nothing herein shall require Tenant to
indemnify, defend or hold harmless Landlord from, and Landlord shall reimburse,
defend, indemnify and hold Tenant, its employees, officers, directors,
shareholders and agents free and harmless from and against any Environmental
Claims arising out of or in anyway connected with any Hazardous Materials
Managed or Released on the Premises by Landlord or its agents, contractors or
employees.



                                  ARTICLE 27.
                       TITLE AND COVENANT AGAINST LIENS

     Landlord's title is and always shall be paramount to the title of Tenant
and nothing contained in this Lease shall empower Tenant to do any act which
can, shall or may encumber the title of Landlord. Tenant covenants and agrees
not to suffer or permit any lien of mechanics or materialmen to be placed upon
or against the Premises, the Building, the Land or against Tenant's leasehold
interest in the Premises and, in case of any such lien attaching, to pay and
remove same immediately. Tenant has no authority or power to cause or permit any
lien or encumbrance of any kind whatsoever, whether created by act of Tenant,
operation of law or otherwise, to attach to or to be placed upon the Premises,
the Building or the Land, and any and all liens and encumbrances created by
Tenant shall attach only to Tenant's interest in the Premises. If any such liens
so attach and Tenant fails to pay and remove or bond over the same within thirty
(30) days, Landlord, at its election, may pay and satisfy the same and in such
event the sums so paid by Landlord, with interest from the date of payment at
the rate set forth in Section 28.08 for amounts owed Landlord by Tenant. Such
sums shall be deemed to be additional rent due and payable by Tenant at once
without notice or demand.


                                  ARTICLE 28.
                                 MISCELLANEOUS

     28.01  Successors and Assigns.  Each provision of this Lease shall extend
to and shall bind and inure to the benefit not only of Landlord and Tenant, but
also of their respective heirs, legal representatives, successors and assigns,
but this provision shall not operate to permit any transfer, assignment,
mortgage, encumbrance, lien, charge or subletting contrary to the provisions of
this Lease.


                                     -46-
<PAGE>
 
     28.02  Modifications in Writing.  No modification, waiver or amendment of
this Lease or of any of its conditions or provisions shall be binding upon
Landlord unless in writing and signed by Landlord.

     28.03  No Option; Irrevocable Offer.  Submission of this instrument for
examination shall not constitute a reservation of or option for the Premises or
in any manner bind Landlord and no lease or obligation on Landlord shall arise
until this instrument is signed and delivered by Landlord and Tenant; provided,
however, the execution and delivery by Tenant of this Lease to Landlord or the
agent of Landlord's beneficiary, if any, shall constitute an irrevocable offer
by Tenant to lease the Premises on the terms and conditions contained herein,
which offer may not be revoked for thirty (30) days after such delivery.

     28.04  Financial Statements.  Tenant shall furnish Landlord annually within
ninety (90) days after the end of Tenant's fiscal year with a copy of its annual
audited and certified statement, prepared in accordance with generally accepted
accounting principles and certified by a reasonable financial officer of Tenant.
Tenant agrees that Landlord may deliver a copy of such statements to its
mortgagee or ground lessor, but otherwise Landlord shall treat such statements
and information contained therein, to the extent not otherwise available to the
public, as confidential.

     28.05  Definition of Landlord.  The term "Landlord" as used in this Lease
means only the owner or owners at the time being of the Building so that in the
event of any assignment, conveyance or sale, once or successively, of said
Building, or any assignment of this Lease by Landlord, said Landlord making such
sale, conveyance or assignment shall be and hereby is entirely freed and
relieved of all covenants and obligations of Landlord hereunder accruing after
such sale, conveyance or assignment, and Tenant agrees to look solely to such
purchaser, grantee or assignee with respect thereto who shall be deemed to have
assumed such covenants and obligations occurring after such sale, conveyance or
assignment. This Lease shall not be affected by any such assignment, conveyance
or sale, and Tenant agrees to attorn to the purchaser, grantee or assignee.

     28.06  Headings.  The headings of Articles and Sections are for convenience
only and do not limit, expand or construe the contents of the Articles or
Sections.

     28.07  Time of Essence.  Time is of the essence of this Lease and of all
provisions hereof.

     28.08  Default Rate of Interest.  All amounts, including, without
limitation, Base Rent and Rent Adjustments, owed by Tenant to Landlord pursuant
to any provision of this Lease shall bear interest from the date due until paid
at the annual rate of five percent (5%) in excess of the rate of interest
announced from time to time by The First National Bank of Chicago, as its prime,
reference or corporate base rate, changing as and when said prime, reference or
corporate base rate changes, unless a lesser rate shall then be the maximum rate
permissible by law with respect thereto, in which event said lesser rate shall
be charged.

     28.09  Severability.  The invalidity of any provision of this Lease shall
not impair or affect in any manner the validity, enforceability or effect of the
rest of this Lease.

                                     -47-
<PAGE>
 
     28.10  Entire Agreement.  All understandings and agreements, oral or
written, heretofore made between the parties hereto are merged in this Lease,
which alone fully and completely expresses the agreement between Landlord (and
its beneficiaries, if any, and their agents) and Tenant.


                                  ARTICLE 29.
                            EXCULPATORY PROVISIONS

     It is understood and agreed expressly by and between the parties hereto,
anything herein to the contrary notwithstanding, that each and all of the
representations, warranties, covenants, undertakings and agreements made herein
on the part of Landlord, while in form purporting to be the representations,
warranties, covenants, undertakings and agreements of Landlord, are nevertheless
each and every one of them made and intended, not as personal representations,
warranties, covenants, undertakings and agreements by Landlord or for the
purpose or with the intention of binding Landlord personally, but are made and
intended for the purpose only of subjecting Landlord's interest in the Building,
the Land and the Premises to the terms of this Lease and for no other purpose
whatsoever, and in case of default hereunder by Landlord (or default through,
under or by any of its beneficiaries, or agents or representatives of said
beneficiaries), Tenant shall look solely to the interests of Landlord in the
Building and Land; that this Lease is executed and delivered by Landlord not in
its own right, but solely in the exercise of the powers conferred upon it as
trustee; that neither Landlord nor any of Landlord's beneficiaries shall have
any personal liability to pay any indebtedness accruing hereunder or to perform
any covenant, either express or implied, contained herein and no liability or
duty shall rest upon Landlord to sequester the trust estate or the rents, issues
and profits arising therefrom, or the proceeds arising from any sale or other
disposition thereof; and that no personal liability or personal responsibility
of any sort is assumed by, nor at any time shall be asserted or enforceable
against, said Landlord, individually or personally, but only as trustee under
the provisions of the trust agreement establishing the trust, or against any of
the beneficiaries under the trust agreement establishing the trust on account of
this Lease or on account of any representation, warranty, covenant, undertaking
or agreement of Landlord contained in this Lease, either express or implied, all
such personal liability, if any, being expressly waived and released by Tenant
and by all persons claiming by, through or under Tenant.

                                     -48-
<PAGE>
 
     IN WITNESS WHEREOF, the parties hereto have caused this Lease to be
executed as of the date first written above.

                              LANDLORD:
 
                              BANK ONE, ILLINOIS, N.A., not personally but
                              solely as Trustee as aforesaid

                                       RIDER ATTACHED HERETO IS HEREBY 
                              By:       EXPRESSLY MADE A PART HEREOF.
                                  ------------------------------------------
                                  Its:
                                      --------------------------------------



                              TENANT:

                              MAY & SPEH, INC., a Delaware corporation


                              By: /s/ 
                                  ------------------------------------------
                                  Its: Executive Vice President, CFO
                                       -------------------------------------


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                                    RIDER A

                                   BASE RENT


(a)  The annual Base Rent payable by Tenant for Term and the Extended Terms
     shall be as follows:

     (i)  First Phase Commencement Date through August 31, 2004.

          The annual Base Rent for each Office Space Phase for the period
          commencing on the Phase Commencement Date for such Space and ending on
          the Commencement Date shall be an amount equal to one third of the
          product of (x) the Fixed Rental Rate and (y) 50,000.  The annual Base
          Rent for the period commencing on the Commencement Date and ending
          August 31, 2004, shall be an amount equal to the product of (x) the
          Fixed Rental Rate and (y) 150,000.  The annual Base Rent computed
          pursuant to the preceding two sentences shall be subject to adjustment
          as follows:

          (A)  If Tenant occupies any portion of the second and third floors of
               the Building prior to September 1, 2000 for the conduct of its
               business (including for storage space), then effective as of the
               date of such occupancy, the annual Base Rent shall be increased
               by the product of (i) the Fixed Rental Rate, (ii) 50,000 and
               (iii) the deemed equivalent of the percentage of such floors
               occupied by Tenant;

          (B) The annual Base Rent for the period commencing September 1, 2001
              and ending August 31, 2004, shall not be less than an amount equal
              to the product of (x) the Fixed Rental Rate and (y) 175,000;

          (C) The annual Base Rent for the period commencing September 1, 2003
              and ending August 31, 2004, shall not be less than an amount equal
              to the product of (x) the Fixed Rental Rate and (y) 200,000.

     (ii) September 1, 2004 to August 31, 2009.
         
          The annual Base Rent for the period commencing September 1, 2004 and
          ending on August 31, 2009, shall be an amount equal to the product of
          (A) the Fixed Rental Rate, (B) 200,000 and (C) the greater of (x) 1.03
          and (y) the lesser of (aa) 1.06 and (bb) the average annual percentage
          increase, if any, in the CPI between August 1998 and August 2004.

     (iii)September 1, 2009 through August 31, 2014.

          The annual Base Rent for the period commencing September 1, 2009 and
          ending August 31, 2014 shall be an amount equal to the product of (A)
          the annual Base Rent in effect for August 2009, and (B) the greater of
          (x) 1.03 and (y) the lessee of (aa) 1.06 and (bb) the average annual
          percentage increase in the CPI between August, 2004 and August 2009.
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     (iv)   September 1, 2014 through the last day of the initial Term.

            The annual Base Rent for the period commencing September 1, 2014 and
            ending on the last day of the initial Term shall be an amount equal
            to the product of (A) the annual Base Rent in effect for August 2014
            and (B) the greater of (x) 1.03 and (y) the lesser of (aa) 1.06 and
            (bb) the average annual percentage increase in the CPI between
            August 2009 and August 2014.

     (v)    First Extended Term.

            The annual Base Rent for the First Extended Term, shall be an amount
            equal to the greater of (1) the Market Rent for the Premises for the
            First Extended Term and (2) the product of (A) the annual Base Rent
            in effect on the last day of the Term and (B) the greater of (x)
            1.03 and (y) the lesser of (aa) 1.06 and (bb) the average annual
            percentage increase, if any, in the CPI between August 2014 and the
            month preceding the commencement of the First Extended Term.

     (vi)   Second Extended Term.

            The annual Base Rent for the Second Extended Term, shall be an
            amount equal to the greater of (1) the Market Rent for the Premises
            for the Second Extended Term and (2) the product of (A) the annual
            Base Rent in effect on the last day of the First Extended Term and
            (B) the greater of (x) 1.03 and (y) the lesser of (aa) 1.06 and (bb)
            the average annual percentage increase if any, in the CPI between
            the month preceding the commencement of the First Extended Term and
            the month preceding the commencement of the Second Extended Term.

     (vii)  Third Extended Term.

            The annual Base Rent for the Third Extended Term, shall be an amount
            equal to the greater of (1) the Market Rent for the Premises for the
            Third Extended Term and (2) the product of (A) the annual Base Rent
            in effect on the last day of the Second Extended Term and (B) the
            greater of (x) 1.03 and (y) the lesser of (aa) 1.06 and (bb) the
            average annual percentage increase, if any, in the CPI between the
            month preceding the commencement of the Second Extended Period and
            the preceding the commencement of month of the Third Extended
            Period.

     If the annual Base Rent for any period described above cannot be determined
as of the first day of such period, then until such amount is determined, Tenant
shall pay Base Rent at the minimum rate set forth for such period (or, in the
case of the Base Rent as of Commencement Date, assuming the Fixed Rental Rate
was $13.60). When the actual annual Base Rent is determined, Landlord shall
notify Tenant in writing of such amount within thirty (30) days thereafter and
Tenant, in the case of an underpayment, shall pay to Landlord any additional
Base Rent due for the portion of such period prior to the date of such payment,
or Landlord, in the case of an overpayment, shall pay to Tenant the amount of
such overpayment.

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     If Tenant exercises its option to extend the Term for an Extended Term,
then within thirty (30) days after receipt of Tenant's notice exercising the
Extension Option (or, if later, eight (8) months prior to the end of the then
Term), Landlord shall notify Tenant of its determination of the Market Rent for
the Extended Term in question. If the Market Rent determined by Landlord is
greater than the Base Rent determined pursuant to clause (2) of paragraphs
(a)(v), (vi) or (vii) above, as the case may be, then within thirty (30) days
after receipt of Landlord's notice of the Market Rent, Tenant shall elect in a
written notice ("Tenant's Rent Determination Notice"), delivered to Landlord
either (i) to accept Landlord's determination of the Market Rent or (ii) to have
the Market Rent determined by appraisal pursuant to paragraph (c) below, in
which event Tenant shall also set forth its determination of the Market Rent. If
Tenant fails to timely deliver such notice, Tenant will be deemed to have
accepted Landlord's determination of the Market Rent.

(b)  As used in this Rider A and in the Lease:

     (i)    "Adjusted Rental Costs" shall mean:

            (A)  An amount equal to the product of (1) the Maximum Project Cost,
                 (2) the annual constant necessary to amortize the Maximum Total
                 Project Cost with interest at the Amortization Rate over 
                 twenty-five (25) years, and (3) 1.1; reduced by

            (B)  $1,500,262.40, which amount is the annual Base Rent payable
                 under the 1501 Lease.

     (ii)   "Amortization Rate" shall mean 200 basis points over the annual
            yield on ten (10) year United States Treasury Bills issued on a date
            prior to the Commencement Date selected by Landlord. Within thirty
            (30) days after selection of such date Landlord shall advise Tenant
            in writing of the date to be used to determine the Amortization Rate
            and such rate.

     (iii)  "CPI" shall mean the Revised Consumer Price Index for Urban Wage
            Earners and Clerical Workers, All Items (base index year 1982-
            84=100), for Chicago, Gary, Lake County, IL-IN-WI, as published by
            the United States Department of Labor, Bureau of Labor Statistics.
            If the manner in which the Consumer Price Index is determined by the
            Bureau of Labor Statistics shall be substantially revised,
            including, without limitation, a change in the base index year, a
            reasonable adjustment shall be made by Landlord in such revised
            index which would produce results equivalent, as nearly as possible,
            to those which would have been obtained if such Consumer Price Index
            had not been so revised. If the Consumer Price Index shall become
            unavailable to the public because publication is discontinued, or
            otherwise, or if equivalent data is not readily available to enable
            Landlord to make the adjustment referred to in the preceding
            sentence, then Landlord will substitute therefor a comparable index
            based upon changes in the cost of living or purchasing power of the
            consumer dollar published by any other governmental agency or, if no
            such index is available, then a comparable

                                      -3-
<PAGE>
 

            index published by a university, a major bank or other financial
            institution, or a comparable and recognized financial publication.

     (iv)   "Fixed Rental Rate" shall mean the Adjusted Rental Costs divided by
            200,000;

     (v)    "Maximum Project Cost" shall mean the sum of (A) the portion of the
            Total Project Costs (exclusive of Second Floor Construction
            Allowance, the Costs of Office Improvements and Costs due to Changes
            (other than Landlord Scope Changes and Tenant Delays) not in excess
            of $34,861,257 and (B) the portion of the Costs of Office
            Improvements, Costs due to Changes (other than Landlord Scope
            Changes) and Tenant Delays, not in excess of $6,000,000.

     (vi)   "Market Rent" shall mean the then prevailing market rental rate per
            rentable square foot of area for space comparable to the space to be
            leased by Tenant pursuant for the term of the lease of such space,
            taking into account applicable loss factors, applicable lengths of
            lease term, the creditworthiness of the tenants, differences in the
            size of the space leased, the then market rental conditions, the
            condition of the subject premises and comparable space, the location
            of amenities in the Building and comparable buildings, the fact that
            this Lease is a triple net Lease, differences in operating expenses
            and taxes, Rent Concessions and other factors normally taken into
            account in determining fair market rent. As used herein, "Rent
            Concessions" means market rent credits or abatements, lease buy-outs
            or takeovers, the work letters and tenant improvement construction
            allowances provided under leases for comparable space and other
            market tenant inducement concessions. Market Rent shall be
            determined as a rate net of all Rent Concessions.

     (vii)  "Total Project Costs" shall mean the sum of (A) the Costs, as
            defined in Section 2.08 of the Lease, (B) all costs expended by
            Landlord to acquire the land and Building described in the 1501
            Lease, (C) the $500,000 Repair Allowance provided Tenant under the
            1501 Lease and (D) to the extent paid by Landlord the $1,250,000
            Vacant Space Construction Allowance provided Tenant under Section
            S.3 of this Lease. Within 180 days after the Commencement Date,
            Landlord shall send Tenant a notice setting forth in detail the
            Total Project Costs exclusive of the Repair Allowance and Second
            Floor Construction Allowance.

(c)  If the Market Rent is to be determined by appraisal, then:

     (i)    No later than fifteen (15) days following Tenant's Rent
            Determination Notice, Tenant shall select and retain an individual
            as an appraiser of its choice and give Landlord written notice of
            such appraiser's name, address and telephone number ("Tenant's
            Selection Notice").

     (ii)   Within twenty (20) days after receipt of Tenant's Selection Notice,
            Landlord shall select and retain an appraiser of its choice and give
            Tenant written notice of such appraiser's name, address and
            telephone number ("Landlord's Selection Notice").

                                      -4-

<PAGE>
 

     (iii)  The appraisers so selected by Tenant and Landlord shall then select
            an individual as a third appraiser within five (5) days after
            receipt by Tenant of Landlord's Selection Notice and furnish
            Landlord and Tenant written notice of such appraiser's name, address
            and telephone number and Landlord and Tenant shall retain the
            services of such third appraiser.

     (iv)   Within fifteen (15) days following selection of the appraisers,
            Landlord and tenant shall each simultaneously submit to the other
            their respective determinations of the Market Rent. During the next
            seven (7) days both Landlord and Tenant shall prepare a written
            critique of the other's determination and on the seventh (7th) day
            Landlord's and Tenant's determinations (as previously submitted to
            the other party with no modifications or additions whatsoever) and
            Landlord's and Tenant's critiques shall be submitted to the
            appraisers.

     (v)    The three (3) appraisers shall then determine by majority vote
            whether the Market Rent submitted by Landlord or the Market Rent
            submitted by Tenant is the Market Rent for the Premises for the
            Extended Term in question.

     All appraisers selected pursuant to this paragraph shall have at least ten
     (10) years experience with commercial property in the area where the
     Premises are situated and have an MAI certification or be licensed leasing
     brokers based in Metropolitan Chicago, shall not have a financial interest
     in Landlord or Tenant and shall otherwise be impartial.

     If Tenant fails to appoint its appraiser in the manner and within the time
     specified in (i) above, then the Market Rent shall be the Market Rent
     determined by Landlord. If Landlord fails to appoint its appraiser in the
     manner and within the time prescribed in clause (ii), then such Market Rent
     shall be the Market Rent set forth in the Tenant's Rent Determination
     Notice.

     If the appraisers selected by Tenant and Landlord fail to appoint the third
     appraiser within the time and in the manner prescribed in clause (iii)
     above, then Landlord and Tenant shall jointly and promptly apply to the
     local office of the American Arbitration Association for the appointment of
     the third appraiser.

     The decision of the appraisers shall be binding, final and conclusive on
     the parties (unless it shall be manifest that the appraiser or one or more
     of the appraisers shall not be an impartial person) and shall be
     enforceable by either party in a court of competent jurisdiction. The cost
     of the foregoing appraisal process (including any court costs) shall be
     borne equally by the parties).

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