<PAGE>   1
                                                                   EXHIBIT 10.13





                             OFFICE LEASE AGREEMENT

                                     between

              FIRST CAMPBELL ASSOCIATES, L.C., LOUDOUN CENTER L.C.,
           FAIRFAX CORNER ASSOCIATES L.C., BLUE RIDGE ASSOCIATES L.C.,
              MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
                           (collectively, "Landlord")

                                       and

                          DIGITAL COMMERCE CORPORATION
                             a Delaware corporation
                                   ("Tenant")




                                       1
<PAGE>   2


                             OFFICE LEASE AGREEMENT

         THIS OFFICE LEASE AGREEMENT (this "Lease") is made and entered into
this 24th day of January, 2000, by and between FIRST CAMPBELL ASSOCIATES, L.C.,
LOUDOUN CENTER L.C., FAIRFAX CORNER ASSOCIATES L.C., BLUE RIDGE ASSOCIATES L.C.,
MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C., all Virginia limited
liability companies (collectively, "Landlord") and DIGITAL COMMERCE CORPORATION,
a Delaware corporation ("Tenant"), upon all terms set forth in this Lease and in
all Exhibits hereto, to each and all of which terms Landlord and Tenant hereby
mutually agree, and in consideration of One Dollar and other valuable
considerations, the receipt and sufficiency of which are hereby acknowledged,
and of the rents, agreements and benefits flowing between the parties hereto, as
follows:


                                    ARTICLE 1
                 BASIC LEASE INFORMATION AND CERTAIN DEFINITIONS

         Section 1.01. Each reference in this Lease to information and
definitions contained in Article 1 and each use of the terms capitalized and
defined in this Section 1.01 shall be deemed to refer to, and shall have the
following meanings:

         A.       Building:         Dulles Overlook
                                    575 Herndon Parkway
                                    Herndon, Virginia 20170

         B.       Premises: The Premises located on the entire third (3rd) floor
                  of the Building, as more fully described and shown on the
                  floor plan attached as Exhibit "A".

         C.       Term: Commencing on the Commencement Date and shall end five
                  (5) years after the Rent Commencement Date.

         D.       Estimated Delivery Date: February 1, 2000.

         E.       Rent Commencement Date: That date which is ninety (90) days
                  after the Commencement Date.

         F.       Expiration Date: The date that is five (5) years after the
                  Rent Commencement Date.

         G.       Rentable Area of the Building: 135,375 square feet.

         H.       Rentable Area of the Premises: 28,575 square feet.

         I.       Tenant's Proportionate Share: 21.11%.

         J.       Base Rent: $785,812.50 per year ($65,484.38 per month), which
                  amount is based upon $27.50 per square foot of Rentable Area
                  in the Premises per year.

         K.       Base Operating Expenses Amount: The actual Base Operating
                  Expenses for the Building incurred during Calendar Year 2000.

         L.       Base Real Estate Taxes Amount: The actual Real Estate Taxes
                  assessed against the Building or against Landlord for the
                  Calendar Year 2000. Appropriate adjustments will be made to
                  the Base Real Estate Taxes to the extent the real estate tax
                  assessment used in determining the Base Real Estate Taxes was
                  not based on a fully assessed value for the Building.

         M.       Adjustment Factor: Two and one-half percent (2 1/2%).

         N.       Security Deposit: $300,000.00, subject to adjustment pursuant
                  to Part 23 of the General Lease Provisions attached hereto as
                  Exhibit "C".


                                       2
<PAGE>   3


         O.       Landlord's Address for Notices:

                           c/o The Peterson Companies L.C.
                           12500 Fair Lakes Circle
                           Suite 400
                           Fairfax, Virginia 22033
                           Attention:  Asset Manager for 575 Herndon Parkway

         P.       Tenant's Address for Notices:

                           Before the Commencement Date:

                           Digital Commerce Corporation
                           11180 Sunrise Valley Drive
                           Reston, VA 20191
                           Attn: Controller

                           After the Commencement Date:

                           Digital Commerce Corporation
                           575 Herndon Parkway, Suite 300
                           Herndon, VA 20170
                           Attn: Controller

         Q.       Lease: Collectively refers to this Office Lease Agreement
                  together with the following Exhibits which are attached hereto
                  and incorporated herein by this reference.

                           Exhibits

                           "A" -- Floor Plans
                           "B" -- Leasehold Improvements
                           "C" -- General Lease Provisions
                           "D" -- Rules and Regulations
                           "E" -- Commencement Date Notice
                           "F" -- Janitorial Cleaning Specifications

         R.       Broker:  Cushman & Wakefield of Virginia, Inc.


                                    ARTICLE 2
                                 DEMISE AND TERM

         Landlord leases to Tenant, and Tenant leases from Landlord, the
Premises located in the Building for the Term and subject to the provisions
hereof. During the Term, Tenant and its agents, employees, and invitees, shall
also have the nonexclusive right with others designated by Landlord to the use
of the common areas of the Building and of the land on which the Building is
located for the common areas' intended and normal purpose. Common areas include
elevators, sidewalks, parking areas, driveways, hallways, stairways, public
bathrooms, common entrances, lobby, and other similar public areas and access
ways. The common areas may be changed by Landlord from time-to-time. The Term of
this Lease shall be for the period specified in Section 1.01 and shall begin at
midnight on the Commencement Date (as defined in the General Lease Provisions)
and shall, unless this Lease is sooner terminated in accordance with the
provisions of this Lease, end at midnight on the Expiration Date, provided,
however, that if for any reason the Expiration Date shall be a day other than
the final day of a calendar month then, the Term of this Lease shall be extended
so that it will expire on the last day of the calendar month in which the
Expiration Date takes place.


                                       3
<PAGE>   4

                                    ARTICLE 3
                                 RENEWAL OPTION

         Subject to the expansion rights of other tenants in the Building,
Tenant shall have the right to renew and extend the Term of this Lease with
respect to the Premises then subject to this Lease for the Renewal Term (herein
so called) described below, upon and subject to the following terms and
conditions:

         1. Tenant may extend this Lease for one (1) Renewal Term of five (5)
years by Tenant's giving written notice thereof to Landlord no later than twelve
(12) months prior to the expiration of the original Term. The Renewal Term shall
commence immediately upon the expiration of the original Term and upon exercise
by Tenant of its right to a Renewal Term, the Expiration Date of the Term shall
automatically become the last day of the Renewal Term. If Tenant does not
exercise its rights to a Renewal Term in a timely manner, Tenant's failure shall
conclusively be deemed a waiver of its rights to a Renewal Term.

         2. The exercise by Tenant of its right to the Renewal Term must be
made, if at all, by written notice executed by Tenant and delivered to Landlord
on or before the date set forth above, but not earlier than eighteen (18) months
prior to the expiration of the original Term. Once Tenant shall exercise its
rights to the Renewal Term, Tenant may not thereafter revoke such exercise.
Tenant shall not have the right to exercise the Renewal Term if an Event of
Default under this Lease has occurred and is then continuing, either at the time
Tenant gives notice of its election or immediately prior to the commencement of
the Renewal Term.

         3. Tenant shall take the Premises "as is" for the Renewal Term and
Landlord shall have no obligation to make any improvements or alterations to the
Premises.

         4. Base Rent for the first year of the Renewal Term shall be $30.35 per
square foot of Rentable Area of the Premises. The Base Rent during the Renewal
Term shall thereafter escalate annually on the anniversary date of the
commencement of the Renewal Term in accordance with Section 3.02 of the General
Lease Provisions.

         5. Subject to subparagraph 4 above, the leasing of the Premises for the
Renewal Term shall be upon the same terms and conditions as are applicable for
the original Term, and shall be upon and subject to all of the provisions of
this Lease, including, without limitation, the obligation of Tenant to pay
Tenant's Additional Rent under the Lease.


                                    ARTICLE 4
                          ALLOWANCES GRANTED TO TENANT

         In consideration of Tenant's full, prompt and faithful observance and
performance of its obligations under the Lease, and in reliance thereon,
Landlord hereby grants to Tenant an allowance of $10.00 per square foot of
Rentable Area on the third (3rd) floor of the Premises resulting in a total
allowance of $285,750.00 (the "Tenant Allowance") to be applied by Landlord to
the costs to be borne by Tenant pursuant to Exhibit "B" to the Lease. Tenant
shall use one-half (1/2) of the Tenant Allowance to purchase systems furniture
and case goods from Computer Associates. The balance of the Tenant Allowance may
be used by Tenant to defray other hard and soft costs related to the Premises
including cabling and wiring of the Premises and other costs relating to
Tenant's relocation and moving, including the services of consultants related to
Tenant's project. Landlord shall reimburse Tenant for such costs from the Tenant
Allowance within fifteen (15) days after: (i) presentation to Landlord of
receipts and invoices for such work and/or materials, and (ii) Landlord shall
have received copies of satisfactory final lien waivers from all contractors,
subcontractors and materialmen with respect to alterations, installations and
other work performed in and about the Premises. Landlord shall not be obligated
to release any Tenant Allowance money if Tenant has not posted the entire
Security Deposit, or if any other Event of Default has occurred. Landlord shall
have a security lien as provided in Part 24 of the General Lease Provisions.

         Provided that no Event of Default under this Lease has occurred, Tenant
may elect to apply up to $91,440.00 of the balance of the Tenant Allowance
toward monthly Base Rent until the said portion of the Tenant Allowance is
exhausted; provided, however, that the amount so applied to


                                       4
<PAGE>   5


Base Rent in any month shall not exceed one-half (1/2) of the amount of Base
Rent payable for that month. Tenant shall notify Landlord of said election
within thirty (30) days of the execution date of this Lease by written notice
specifying the amount to be so applied (up to one-half (1/2) of monthly Base
Rent) and authorizing Landlord to deduct the amount from the Tenant Allowance.
Such notice by Tenant shall be irrevocable.

         Without limiting any remedies available to Landlord for Tenant's
Default hereunder, in the Event of Default hereunder such that (in each case,
whether with or without legal proceedings) Landlord recovers possession of the
Premises, or such that Tenant's right to possession of the Premises is
terminated, or such that this Lease is terminated, then, in such event, the then
unrecovered portion of the Tenant Allowance shall become immediately due and
payable to Landlord. For purposes of the preceding sentence, the Tenant
Allowance shall be deemed recovered on a straight-line basis over the Term with
each full payment of Base Rent, commencing on first month after the Rent
Commencement Date in which Tenant pays full Base Rent. For example, assuming
that none of the Tenant Allowance is applied to Base Rent in accordance with
this Article 4 and further assuming that the Premises is not expanded pursuant
to Article 5 hereof, if this Lease is terminated as a result of Tenant's default
after Tenant has paid full Base Rent for twenty-four months, then the
unrecovered portion of the Tenant Allowance would be 60%, calculated as
((60-24)/60) *100.


                                    ARTICLE 5
                      RIGHT OF FIRST OFFER; EXPANSION RIGHT

         Section 5.01 From the execution date of this Lease until February 15,
2000 (the "Expansion Period"), and provided that Tenant is not in Default under
this Lease at the applicable time, Tenant, shall, in the manner described by and
in compliance with the terms and provisions of this Section 5.01, have a
non-assignable and non-transferable right of first offer to expand the Premises
to include all or any portion of the Expansion Space (hereinafter defined).
Notwithstanding the foregoing, said right of first offer to expand the Premises
shall be assigned to an Affiliate upon assignment of Tenant's entire interest in
this Lease to that Affiliate, in accordance with and subject to Section 15.04 of
the General Lease Provisions.

         (a) If at any time during the Expansion Period, Landlord shall either
(i) receive a bona-fide offer from a third party to lease all or a portion of
the Expansion Space, which Landlord is prepared to accept, or (ii) prepare a
proposal pertaining to all or a portion of the Expansion Space which Landlord is
prepared to offer as a lease proposal to a third party, then in either such
event, Landlord shall send a written notice (the "Offer Notice") to Tenant of
such proposal. The Offer Notice shall set forth in reasonable detail the size or
portion of the Expansion Space subject to the Offer Notice, and shall contain
(or be deemed to contain) an offer to Tenant to lease the portion of the
Expansion Space subject to the Offer Notice at the same rental rate and on the
same terms and conditions set forth in the Lease, except that the Tenant
Allowance applicable to the Expansion Space shall be $5.00 per square foot of
Rentable Area in the Expansion Space and the Rent Commencement Date applicable
to the Expansion Space shall be sixty (60) days after the later of: (i) the date
of the Offer Notice, or (ii) the date Landlord delivers or tenders possession of
the Expansion Space to Tenant. Tenant may elect to accept the Offer Notice, by
giving written notice to Landlord of its election not more than five (5)
business days after receipt by Tenant of the Offer Notice. Any election by
Tenant shall be irrevocable.

         (b) In the event Tenant responds within the five (5) business day
period and elects to accept the proposal set forth in the Offer Notice, then
this Lease shall automatically be amended to include within the Premises,
effective as of the effective date set forth in the Offer Notice, the portion of
the Expansion Space subject to the Offer Notice. The rental rate, terms and
conditions of this Lease shall apply to the portion of the Expansion Space
covered by the Offer Notice except that the Tenant Allowance applicable to the
Expansion Space shall be $5.00 per square foot of Rentable Area in the Expansion
Space, and the Rent Commencement Date applicable to the Expansion Space shall be
sixty (60) days after the later of: (i) the date of the Offer Notice, or (ii)
the date Landlord delivers or tenders possession of the Expansion Space to
Tenant. Any election by Tenant shall be irrevocable. The provisions of this
subparagraph shall be self-enforcing without the need for any further act by
Landlord or Tenant. However, upon request by either party, Landlord and Tenant
shall execute an amendment to this Lease confirming such


                                       5
<PAGE>   6


exercise (including, without limitation, the increased Rentable Area of the
Premises, Security Deposit, Base Rent and Tenant's Proportionate Share).

         (c) Should Tenant either fail to respond within the five (5) business
day period, or elects not to accept the Offer Notice, then Tenant shall be
deemed to have elected not to accept the Offer Notice, the portion of the
Expansion Space subject to the Offer Notice shall thereafter be automatically
excluded from the Expansion Space and the rights of Tenant under this Lease, as
they pertain to the portion of the Expansion Space which is subject to the Offer
Notice, shall automatically terminate and be of no further force or effect. The
provisions of this subparagraph shall be self-enforcing without the need for any
further act by Landlord or Tenant.

         Section 5.02:

         (a) Provided Tenant is not in Default under this Lease at the
applicable time, and further provided that Landlord has not sent Tenant any
Offer Notice, Tenant, during the Expansion Period, shall, in the manner
described by and in compliance with the terms and provisions of this Section
5.02, have a non-assignable and non-transferable right to expand the Premises to
include the entire Expansion Space. Notwithstanding the foregoing, said right to
expand the Premises shall be assigned to an Affiliate upon assignment of
Tenant's entire interest in this Lease to that Affiliate, in accordance with and
subject to Section 15.04 of the General Lease Provisions. Said expansion right
may be exercised as to the entire Expansion Space only, and may not be exercised
as to less than the whole Expansion Space.

         (b) Tenant may exercise its right to expand the Premises to include the
Expansion Space by giving written notice (the "Election Notice") to Landlord of
its election no later than the last day of the Expansion Period. Upon Landlord's
receipt of Tenant's Election Notice, this Lease shall automatically be amended
to include within the Premises the Expansion Space. The rental rate, terms and
conditions of this Lease shall apply to the Expansion Space except that the
Tenant Allowance applicable to the Expansion Space shall be $135,645.00 (being
$5.00 per square foot of Rentable Area in the Expansion Space), and the Rent
Commencement Date applicable to the Expansion Space shall be ninety (90) days
after the later of: (i) the date of the Election Notice, or (ii) the date
Landlord delivers or tenders possession of the Expansion Space to Tenant. Any
election by Tenant shall be irrevocable. The provisions of this subparagraph
shall be self-enforcing without the need for any further act by Landlord or
Tenant. However, upon request by either party, Landlord and Tenant shall execute
an amendment to this Lease confirming such exercise (including, without
limitation, the increased Rentable Area of the Premises, Security Deposit, Base
Rent and Tenant's Proportionate Share).

         (c) Should Tenant fail to exercise its rights by delivering an Election
Notice to Landlord prior to the expiration of the Expansion Period, then the
rights of Tenant under this Lease to the Expansion Space shall automatically
terminate. The provisions of this subparagraph shall be self-enforcing without
the need for any further act by Landlord or Tenant.

         Section 5.03 If Tenant elects to expand the Premises, as provided in
Sections 5.01 or 5.02 hereof, then:

                  (i) The Expiration Date of the Lease shall automatically be
extended by two (2) years so that the Term shall be seven (7) years from and
after the Rent Commencement Date of the original Premises; and

                  (ii) The Security Deposit shall be increased by an amount
equal to $11.00 per square foot of Rentable Area of Expansion Space incorporated
within the Premises (the "Additional Security"). The Additional Security shall
be received by Landlord within five (5) business days after the date of Tenant's
written Election Notice or the date of Tenant's written notice per Section
5.01(b) hereof, whichever is applicable. If the Additional Security is not
received within such five (5) business day period, then Tenant's election to
expand the Premises and Tenant's further rights under this Article 5 shall be
considered null and void. Provided that Tenant does not Default under this
Lease, then as provided in and subject to Section 23.04 of the Lease, on each
annual anniversary of the original Premises' Rent Commencement Date, the
Security Deposit and the Additional Security shall be reduced on a straight-line
basis so that on the first day of the last year


                                       6
<PAGE>   7


of the original Term the total amount of the Security Deposit shall be the sum
of $100,000.00 plus $3.69 per square foot of Rentable Area of Expansion Space
incorporated within the Premises; and

                  (iii) The first sentence of Article 3 hereof shall be
automatically amended by deleting the words "Subject to the expansion rights of
other Tenants in the Building"; and

                  (iv) The first sentence of subsection (4) of Article 3 hereof
shall be automatically replaced with the following: "Base Rent for the first
year of the Renewal Term shall be $31.89 per square foot of Rentable Area of the
Premises"; and

                  (v) Notwithstanding anything herein to the contrary, for each
month between the Commencement Date and the Rent Commencement Date, and for each
month following the Rent Commencement Date for which any portion of the Tenant
Allowance is applied toward monthly Base Rent (the "Initial Period"), Tenant
shall pay on a monthly basis, without demand, as Additional Rent for the
Premises, one-twelfth (1/12th) of the Tenant's Proportionate Share of: (i) the
Operating Expenses (as defined in Section 4.01 (b) of the General Lease
Provisions), and (ii) the Real Estate Taxes (as defined in Section 4.02 (c) of
the General Lease Provisions). The terms and conditions of the General Lease
Provisions pertaining to Additional Rent shall apply during the Initial Period
except that no base amount shall be deducted from the Operating Expenses or the
Real Estate Taxes for purposes of calculating Tenant's Additional Rent during
the Initial Period. After the Initial Period, Additional Rent shall be payable
in accordance with the General Lease Provisions.

         Section 5.04 As used in this Article 5, the term "Expansion Space"
shall mean and refer to approximately 27,129 square feet of Rentable Area in the
Building comprising the entire second floor of the Building as the same is shown
on Exhibit "A-1" attached hereto. If Tenant elects to expand the Premises as
provided in this Article 5, Tenant shall take the Expansion Space in its "as is"
and "where is" condition.


                                    ARTICLE 6
                            GENERAL LEASE PROVISIONS

         As set forth in Section 1.01 of the Office Lease Agreement, this Lease
includes and incorporates the General Lease Provisions attached hereto as
Exhibit "C". As more fully set forth in the General Lease Provisions, this Lease
sets forth the entire agreement between Landlord and Tenant relating to the
Premises and the Building. The parts of this Lease which are written, printed,
or typewritten shall have no greater force or effect than and shall not control
over other parts of the Lease, but all parts shall be given equal effect.





                        [SIGNATURES FOLLOW ON NEXT PAGE.]



                                       7
<PAGE>   8


         WITNESS the following signatures and seals of Landlord and Tenant made
as of the date first above written.

                                       LANDLORD:

                                       FIRST CAMPBELL ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:   /s/ William E. Peterson
                                             -----------------------------------
                                       Name: William E. Peterson
                                       Its:  Manager

                                       LOUDOUN CENTER L.C.
                                       a Virginia limited liability company

                                       By:   /s/ William E. Peterson
                                             -----------------------------------
                                       Name: William E. Peterson
                                       Its:  Manager

                                       FAIRFAX CORNER ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:   /s/ William E. Peterson
                                             -----------------------------------
                                       Name: William E. Peterson
                                       Its:  Manager

                                       BLUE RIDGE ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:   /s/ William E. Peterson
                                             -----------------------------------
                                       Name: William E. Peterson
                                       Its:  Manager

                                       MIRROR RIDGE ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:   /s/ William E. Peterson
                                             -----------------------------------
                                       Name: William E. Peterson
                                       Its:  Manager

                                       KING STREET II L.C.
                                       a Virginia limited liability company

                                       By:   /s/ William E. Peterson
                                             -----------------------------------
                                       Name: William E. Peterson
                                       Its:  Manager


                                       TENANT:

                                       DIGITAL COMMERCE CORPORATION
                                       a Delaware corporation

                                       By:   /s/ William H. Seippel
                                             -----------------------------------
                                       Name: William H. Seippel
                                       Its:  Chief Financial Officer and
                                             Director



                                       8

<PAGE>   9


                              EXHIBIT "A" TO LEASE


                           Floor Plan of the Premises

                             Third Floor of Building


                          [FLOOR PLAN OF THE PREMISES]



                                       A-1

<PAGE>   10


                             EXHIBIT "A-1" TO LEASE


                        Floor Plan of the Expansion Space


                        [FLOOR PLAN OF THE EXPANSION SPACE]



                                     A-1-1
<PAGE>   11


                              EXHIBIT "B" TO LEASE

                                     Between

              FIRST CAMPBELL ASSOCIATES, L.C., LOUDOUN CENTER L.C.,
           FAIRFAX CORNER ASSOCIATES L.C., BLUE RIDGE ASSOCIATES L.C.,
              MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
                           (collectively, "Landlord")

                                       and

                          DIGITAL COMMERCE CORPORATION
                                   ("Tenant")


                             Leasehold Improvements

         This Exhibit "B" is attached to and made a part of that certain Office
Lease Agreement dated January 24, 2000 (the "Lease"), between FIRST CAMPBELL
ASSOCIATES, L.C., LOUDOUN CENTER L.C., FAIRFAX CORNER ASSOCIATES L.C., BLUE
RIDGE ASSOCIATES L.C., MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
(collectively, "Landlord"), and DIGITAL COMMERCE CORPORATION, ("Tenant"). The
terms used in this Exhibit that are defined in the Lease shall have the same
meanings as provided in the Lease.

         The purpose of this Exhibit "B" is to set forth the relative rights and
obligations of Landlord and Tenant with respect to the construction and
installation of the initial tenant improvements, it being acknowledged by both
parties that such initial tenant improvements, if any, shall be constructed
after the Commencement Date.

A.       DEFINITIONS

         1. "Building Standard" means the allowances, materials, finishes and
design services required by Landlord for the Building as specified on Schedule 1
attached hereto and incorporated herein.

         2. "Non-Building Standard" means all materials, finishes, and design
services used in connection with the construction and installation of the
Leasehold Improvements which exceed Building Standard allowances or deviate from
Building Standard specifications.

         3. "Landlord's Contractor" means the person or firm from time to time
selected by Landlord to construct and install the Leasehold Improvements in the
Premises.

         4. "Leasehold Improvements" shall mean the aggregate of Building
Standard and Non-Building Standard work in the Premises required by the Approved
Plan.

         5. "Landlord's Architect" shall mean the architect or space planner
engaged by Landlord to prepare the plans and specifications for the Leasehold
Improvements.

         6. "Approved Plan" shall mean the plan for Leasehold Improvements
approved by Landlord and Tenant pursuant to Paragraph D.4. hereof.

B.       GENERAL PROVISIONS

         1. Unless otherwise agreed to in writing by Landlord and Tenant, all
work involved in the design and construction of the Leasehold Improvements shall
be carried out by Landlord's Architect, and Landlord's Contractor under the sole
direction of Landlord. Tenant shall cooperate with Landlord, Landlord's
Contractor, and Landlord's Architect to promote the efficient and expeditious
completion of such work so that completion may occur no later than May 1, 2000
(the "Estimated Completion Date").


                                       B-1
<PAGE>   12


         2. On or before the Estimated Completion Date, Landlord shall use its
best efforts to substantially complete the Leasehold Improvements which are to
be constructed or installed by Landlord in the Premises pursuant to the Approved
Plan.

         3. If the cost to construct the Leasehold Improvements exceeds the
Tenant Allowances stipulated in the Lease, Landlord shall have no obligation to
commence installation of any Leasehold Improvements in the Premises or continue
construction of the Leasehold Improvements until Landlord receives Tenant's
advance payment as described in this Exhibit. Tenant agrees that in the event of
default of payment thereof, Landlord (in addition to other remedies) shall have
the same rights as in the Event of Default of payment of Rent under the Lease
and all delays in the completion of the Leasehold Improvements resulting from
Tenant's non-payment of such deficiency shall constitute Tenant Delay.

C.       DESIGN

         1. Tenant shall devote such time in consultation with Landlord's
Architect as reasonably necessary to enable Landlord's Architect to develop
Tenant's complete working drawings and specifications of the Leasehold
Improvements.

         2. All design, construction and installation shall conform to the
requirements of applicable building, plumbing and electrical codes and the
requirements of any authority having jurisdiction over, or with respect to, such
work.

         3. All architectural, mechanical and electrical plans and
specifications must be approved by Landlord. Any changes in the Approved Plan
must also be approved by Landlord. Tenant shall not be permitted to modify the
Building in any way, including but not limited to the structural, mechanical and
electrical systems, except as approved by Landlord on the Approved Plan. No
alterations by Tenant to the Leasehold Improvements shall be allowed at any time
except as provided in the Lease.

D.       PROCEDURES FOR COMPLETION OF LEASEHOLD IMPROVEMENTS

         The following procedures shall be followed in completing the Leasehold
Improvements.

         1. As soon as reasonably practical after the execution of the Lease,
Tenant shall meet the Landlord's Architect and provide information for design of
a space plan for the Premises.

         2. Landlord's Architect shall complete the space plan and submit the
same to Tenant and Landlord approval. Within ten (10) business days after
Tenant's receipt of such space plan, Tenant shall notify Landlord whether Tenant
approves or disapproves the same.

         3. Upon approval of the space plan by Tenant, Landlord shall cause a
preliminary budget to be prepared indicating the estimated total design and
construction costs to construct the space plan. The budget will indicate the
estimated costs to be borne by both Landlord and Tenant, pursuant to the
allowances set forth in this Lease. Tenant acknowledges that the budget is
merely an estimate of the anticipated costs to improve the Premises generally in
accordance with the space plan, and that the budget is subject to change pending
completion of all design and construction work.

         4. Upon approval of the space plan and budget by Tenant and Landlord,
Landlord's Architect shall be authorized to complete architectural, mechanical,
and electrical working drawings and specifications. Tenant shall provide
Landlord's Architect with any additional information needed for completion of
the working drawings.

         5. Landlord's Architect shall complete working drawings and
specifications and submit the same to Tenant and Landlord for approval. Within
ten (10) business days after Tenant's receipt of such working drawings and
specifications, Tenant shall notify Landlord in writing as to whether Tenant
approves or disapproves such working drawings and specifications.

         6. Upon approval of working drawings by Tenant and Landlord, Landlord
shall, within a reasonable period, have the working drawings bid by several
contractors approved by Landlord.


                                      B-2
<PAGE>   13


Landlord will submit the construction pricing along with all other estimated
costs for design, engineering, permits and Landlord's construction management
fees (not to exceed three percent (3%)) to Tenant for Tenant's approval,
indicating the estimated costs, if any, to be borne by Tenant. Within ten (10)
business days after Tenant's receipt of Landlord's price, Tenant shall notify
Landlord in writing as to whether Tenant approves or disapproves of Landlord's
price. If Tenant fails to notify Landlord within such ten (10) business day
period, Tenant shall be deemed to have approved Landlord's prices. Tenant's
signature on the working drawings, plans and specifications shall acknowledge
Tenant's full acceptance of the working drawings, plans and specifications and
Tenant's binding obligation to pay for all items shown on or in the same as
priced by Landlord. Tenant's failure to sign the working drawings, plans and
specifications within the ten (10) business day period provided for herein shall
be deemed a "Tenant Delay" pursuant to Paragraph F below. Upon approval of
working drawings and specifications by Tenant and Landlord such drawings and
specifications shall be the Approved Plan.

         7. Any costs to be borne by Tenant shall be paid by Tenant to Landlord
as follows:

                  (a) 50% of Tenant's costs shall be paid prior to the
commencement of construction.

                  (b) 50% of Tenant's costs shall be paid upon substantial
completion of the Leasehold Improvements.

         8. Landlord and Landlord's Contractor shall seek all necessary permits
for construction of the Leasehold Improvements. As soon as the permits required
for construction have been obtained, Landlord shall authorize Landlord's
Contractor to commence construction of Leasehold Improvements.

         9. In the event Tenant desires to make any changes or revisions to the
Approved Plan, then any delay in the furnishing, delivery or installation of any
such changed items, including all delays in the revision or working drawings and
specifications, shall be deemed Tenant Delay. The increased cost of such
changes, including any changes by the Landlord's Architect or Contractor, shall
be due from Tenant upon the submission of pricing for such changed items.

E.       DELIVERY OF PREMISES

         1. Tenant is permitted to make periodic inspections of the Premises
during construction provided that such inspections are made during reasonable
business hours and Tenant is accompanied by a representative of Landlord or has
received Landlord's approval. If Tenant enters the Premises or non-public areas
of the Building without Landlord's approval, Tenant shall be deemed to be
trespassing upon the Premises or non-public areas of the Building and Landlord
shall not be liable for any damage or injury sustained by Tenant, or any of
Tenant's agents, representatives or employees arising from Tenant's unauthorized
entry upon the Premises or non-public areas of the Building.

         2. Prior to delivery of possession of the Premises to Tenant or
acceptance of the Premises by Tenant, a final inspection of the Premises shall
be made by Tenant, Landlord, Landlord's Architect, and Landlord's Contractor to
make certain that construction was accomplished in substantial accordance with
the Approved Plan. A punch-list of items which require completion or correction
shall be prepared as a result of final inspection, if necessary. Landlord's
Architect shall have authority to determine when, in his best judgment,
substantial completion of the Leasehold Improvements has been accomplished.

         3. Tenant shall be given possession of the Premises on the Commencement
Date. Landlord shall provide Tenant with reasonable advance notice of the
anticipated date of substantial completion if different than the Estimated
Completion Date. Landlord will promptly complete all punch-list items.

         4. Landlord's Contractor shall be responsible for obtaining the final
inspections and all necessary governmental approvals which are required for
lawful occupancy of the Premises, including the non-residential use permit.


                                      B-3
<PAGE>   14


         5. Nothing contained in this Section E shall be deemed to grant Tenant
any authority to direct Landlord's Architect or Landlord's Contractor in the
performance of their duties during the construction of the Premises.

F.       TENANT DELAY

         Tenant's obligation for payment of Rent under this Lease shall commence
on the Rent Commencement Date, unless such date has been changed and
acknowledged in writing by Landlord and Tenant.

         Landlord shall not be responsible for any delays caused by Tenant which
result in substantial completion of the Leasehold Improvements later than the
Estimated Completion Date nor shall the Commencement Date or the Rent
Commencement Date be modified for such delay. Such delays include, but are not
limited to the following, all such delays being referred to as "Tenant Delay":

         1. Tenant's failure to comply with the procedures for completion of the
Leasehold Improvements outlined in this Exhibit on a timely basis;

         2. Tenant's request for changes or modifications to the work after the
development of the Approved Plan;

         3. Late delivery of or inability to obtain materials required for
Non-Building Standard improvements, provided Landlord informed Tenant of such
issues prior to the start of construction, but in no event shall Landlord be
liable for the delay;

         4. Building code problems related to Non-Building Standard design or
construction, provided Landlord's Architect informed Tenant of such issues prior
to completion of the working drawings, but in no event shall Landlord be liable
for the delay; and

         5. The performance of any work by any person or entity employed or
retained by Tenant.


                                      B-4
<PAGE>   15


                            EXHIBIT "B" - SCHEDULE 1

                          BUILDING STANDARD WORKLETTER
                         DULLES OVERLOOK OFFICE BUILDING


         The following shall constitute the general description and minimum
quality of Building Standard Work, which are utilized in the construction of
Leasehold Improvements. Tenant, at its sole cost (which shall be reimbursable
from the Tenant Allowance, to the extent available), shall have the right, after
consultation with and reasonable approval of the Landlord, to make reasonable
substitutions for specific items described herein, provided that such
substitutions meet or exceed Building Standard Work.

A.       Partitions

         1.       Interior partitions will be constructed of 2 1/2" metal studs
                  at 24" on center, from floor slab to the underside of the
                  finished ceiling, with 1/2" gypsum wallboard panels with taped
                  and finished joints prepared for paint.

         2.       Demising and corridor partitions will be constructed of 2 1/2"
                  studs at 24" on center from floor slab to underside of the
                  deck above with 1/2" gypsum wallboard panels insulated with
                  2 1/2" Batt and with taped and finished joints prepared for
                  paint.

B.       Doors

         1.       Suite Entry Doors shall be single 3'0" x 8'0" solid core,
                  mahogany veneer with building standard finish, and polished
                  stainless steel butt hinges, lever handles, and mortised
                  lockset, keyed to Landlord's master system.

         2.       Tenant Interior Doors shall be 3'0" x 7'0" solid core,
                  painted, with brushed stainless steel lever hardware.

         3.       All doors shall have building standard hollow metal frames.

C.       Ceiling

         1.       Suspended ceilings will consist of a 2' x 2' suspended system
                  with 5/8" acoustical tile in a 1-inch wide grid. The
                  approximate finished ceiling height is 8'6".

D.       Painting

         1.       All partitions, columns and walls will be painted with two
                  coats of flat latex wall paint. Door frames and interior doors
                  will be painted with two coats of semi-gloss enamel. Suite
                  entry doors will be stained and sealed and will match the
                  building standard finish.

E.       Flooring

         1.       Carpeting shall be a minimum of 30 ounce face weight cut pile
                  or 24 ounce face weight loop in a color chosen by Tenant from
                  the manufacturer's standard pallet and approved by Landlord.

         2.       Vinyl composition tile may be substituted for carpet at
                  selected areas such as work rooms, pantries, supply rooms,
                  etc. Color may be chosen by Tenant from the manufacturer's
                  standard pallet as approved by Landlord.

         3.       Vinyl wall base will be provided in all areas receiving carpet
                  or floor tile. Color may be chosen by Tenant from the
                  manufacturer's standard pallet as approved by Landlord.


                                     B-1-1
<PAGE>   16


F.       Electrical

         1.       Lighting Fixtures will be the Building Standard 2' x 4'
                  florescent lights.

         2.       Electric duplex receptacles and light switches will be black
                  with brushed stainless steel or plastic cover plates to match
                  existing.

         3.       Telephone or data outlets will consist of pre-cut openings in
                  the wall with pull strings up to the ceiling. All
                  telephone/data wiring and cover plates are by Tenant's
                  installer and are not considered part of Leasehold
                  Improvements. All telephone/data outlets shall have cover
                  plates.

G.       Heating, Ventilating, Air Conditioning

         1.       A variable air volume (VAV) system provides temperature
                  control to all areas of the Building. Conditioning is provided
                  through light troffer air boots or ceiling diffusers.

H.       Sprinklers and Fire Safety

         1.       An Automatic Sprinkler and Fire Alarm System will be provided
                  in accordance with all national and local codes, including
                  required exit and emergency lights, fire horns, fire hose
                  cabinets and wall mounted extinguishers as required by local
                  authorities. All sprinkler heads shall be recessed.

I.       Window Coverings

         1.       Thin-line horizontal blinds shall match the base building
                  color pallet.


                                     B-1-2

<PAGE>   17


                              EXHIBIT "C" TO LEASE

                                     Between

              FIRST CAMPBELL ASSOCIATES, L.C., LOUDOUN CENTER L.C.,
           FAIRFAX CORNER ASSOCIATES L.C., BLUE RIDGE ASSOCIATES L.C.,
              MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
                           (collectively, "Landlord")

                                       and

                          DIGITAL COMMERCE CORPORATION
                                   ("Tenant")


                            General Lease Provisions
                                Table of Contents


<TABLE>
<S>                                                                          <C>
PART 1 - DELIVERY OF THE PREMISES TO TENANT; RENTABLE AREA...................  1
     Section 1.01.  Commencement Date........................................  1
     Section 1.02.  Delivery of the Premises to Tenant.......................  1
     Section 1.03.  Rentable Area............................................  1
     Section 1.04.  Termination due to Failure to Deliver Possession.........  2
     Section 1.05.  Early Entry by Tenant....................................  2


PART 2 - ACCEPTANCE OF THE PREMISES AND BUILDING BY TENANT...................  2


PART 3 - BASE RENT...........................................................  2
     Section 3.01.  Base Rent................................................  2
     Section 3.02.  Adjustments to Base Rent.................................  2
     Section 3.03.  Payment..................................................  3
     Section 3.04.  Acceptance of Rent.......................................  3
     Section 3.05.  Survival of Rent Obligation..............................  3
     Section 3.06.  Late Payment Fee.........................................  4
     Section 3.07.  Interest on Past Due Rent................................  4


PART 4 - ADDITIONAL RENT.....................................................  4
     Section 4.01.  Operating Expenses.......................................  4
     Section 4.02.  Real Estate Taxes........................................  6
     Section 4.03.  Parking..................................................  7
     Section 4.04.  Additional Rent Defined..................................  7
     Section 4.05.  Rent Defined.............................................  7
     Section 4.06.  Audit by Tenant..........................................  8


PART 5 - SERVICES BY LANDLORD................................................  8


PART 6 - UTILITIES...........................................................  9
     Section 6.01.  Computerized Energy Management System....................  9
     Section 6.02.  Water, Heating, Ventilating and Air Conditioning.........  9
     Section 6.03.  Electricity..............................................  9


PART 7 - USE................................................................. 10
</TABLE>


                                      C-i


<PAGE>   18

<TABLE>
<S>                                                                          <C>
PART 8 - COMPLIANCE WITH LAWS AND BUILDING REGULATIONS....................... 10
     Section 8.01.  Compliance with Laws..................................... 10
     Section 8.02.  Observance of Building's Rules and Regulations........... 10
     Section 8.03.  Hazardous Materials...................................... 10


PART 9 - ALTERATIONS......................................................... 11
     Section 9.01.  Approval of Landlord..................................... 11
     Section 9.02.  Ownership of Improvements to Premises.................... 12


PART 10 - LIENS.............................................................. 12


PART 11 - REPAIRS............................................................ 13
     Section 11.01.  Tenant's Obligations.................................... 13
     Section 11.02.  Landlord's Obligations.................................. 13


PART 12 - INSURANCE.......................................................... 13
     Section 12.01.  Tenant's Insurance...................................... 13
     Section 12.02.  Insurance Rating........................................ 14
     Section 12.03.  Landlord's Insurance.................................... 15
     Section 12.04.  Waiver of Subrogation................................... 15


PART 13 - DAMAGE BY FIRE OR OTHER CASUALTY................................... 15
     Section 13.01.  Damage to Premises...................................... 15
     Section 13.02.  Damage to Building...................................... 15
     Section 13.03.  Partial Damage.......................................... 16
     Section 13.04.  Damage During Last Year of Term......................... 16
     Section 13.05.  No Landlord Liability................................... 16
     Section 13.06.  Apportionment of Rent................................... 16


PART 14 - CONDEMNATION....................................................... 16
     Section 14.01.  Entire Building......................................... 16
     Section 14.02.  Portion of Building..................................... 17
     Section 14.03.  Portion of Premises..................................... 17
     Section 14.04.  Termination of Lease.................................... 17
     Section 14.05.  Landlord's Right to Award............................... 17


PART 15 - ASSIGNMENT AND SUBLETTING.......................................... 17
     Section 15.01.  Rights of Tenants....................................... 17
     Section 15.02.  Excess Rent............................................. 18
     Section 15.03.  Rights of Landlord...................................... 18
     Section 15.04.  Affiliate Transfer...................................... 19


PART 16 - INDEMNIFICATION.................................................... 19


PART 17 - SURRENDER OF THEPREMISES........................................... 19
     Section 17.01.  Condition of Premises................................... 19
     Section 17.02.  Tenant Holdover......................................... 20


PART 18 - ESTOPPEL CERTIFICATES.............................................. 20


PART 19 - SUBORDINATION AND ATTORNMENT....................................... 21
     Section 19.01.  Subordination........................................... 21
     Section 19.02.  Attornment.............................................. 21
     Section 19.03.  Non-Disturbance Agreement............................... 21
</TABLE>

                                      C-ii

<PAGE>   19


<TABLE>
<S>                                                                          <C>
PART 20 - QUIET ENJOYMENT.................................................... 21


PART 21 - SIGNS AND FURNISHINGS.............................................. 22
     Section 21.01.  Signs and Advertisements................................ 22
     Section 21.02.  Furnishings............................................. 22


PART 22 - DEFAULTS AND REMEDIES.............................................. 22
     Section 22.01.  Events of Default....................................... 22
     Section 22.02.  Remedies................................................ 23
     Section 22.03.  Remedies Cumulative..................................... 24
     Section 22.04.  No Acceptance or Surrender.............................. 24
     Section 22.05.  Customs and Practices................................... 24
     Section 22.06.  Payment of Tenant's Obligations by Landlord............. 24
     Section 22.07.  Default by Landlord..................................... 24


PART 23 - SECURITY DEPOSIT................................................... 25
     Section 23.01.  Application of Security Deposit......................... 25
     Section 23.02.  Transfer of Security Deposit............................ 25
     Section 23.03.  Letter of Credit........................................ 25
     Section 23.04.  Reduction of Security Deposit........................... 26


PART 24 - LANDLORD'S LIEN AND SECURITY INTEREST.............................. 26


PART 25 - ATTORNEYS FEES AND LEGAL EXPENSES.................................. 26


PART 26 - NOTICES............................................................ 26


PART 27 - MISCELLANEOUS...................................................... 27
     Section 27.01.  No Partnership.......................................... 27
     Section 27.02.  Brokers................................................. 27
     Section 27.03.  Severability............................................ 27
     Section 27.04.  Trial by Jury........................................... 27
     Section 27.05.  Force Majeure........................................... 27
     Section 27.06.  Captions................................................ 28
     Section 27.07.  Benefit and Burden...................................... 28
     Section 27.08.  No Representations by Landlord.......................... 28
     Section 27.09.  Entire Agreement........................................ 28
     Section 27.10.  No Offer................................................ 28
     Section 27.11.  Authority............................................... 28
     Section 27.12.  Changes Requested by Lender............................. 29
     Section 27.13.  Governing Law and Construction.......................... 29
     Section 27.14.  Landlord's Liability.................................... 29
     Section 27.15.  Use of Name of Building................................. 29
     Section 27.16.  Changes by Landlord..................................... 29
     Section 27.17.  Time of Essence......................................... 30
     Section 27.18.  Satellite Dish.......................................... 30
</TABLE>

                                     C-iii


<PAGE>   20


           PART 1 - DELIVERY OF THE PREMISES TO TENANT; RENTABLE AREA

         SECTION 1.01. COMMENCEMENT DATE.

         The Commencement Date shall be the earliest of the following: (i) the
date on which Tenant takes possession or commences business operations upon the
Premises or any part thereof; or (ii) the date Landlord delivers or tenders the
Premises to Tenant (but in any event not earlier than the Estimated Delivery
Date unless otherwise agreed by Tenant). Upon delivery or tender of the Premises
to Tenant, Landlord and Tenant agree to execute the commencement date notice
(the "Commencement Date Notice") attached hereto as Exhibit "E" and made a part
hereof by this reference. The Premises shall be delivered in its "as is",
broom-clean condition and free of tenants.


         SECTION 1.02. DELIVERY OF THE PREMISES TO TENANT.

         On or before the Estimated Delivery Date, Landlord shall use its best
efforts to deliver the Premises in broom clean condition to Tenant. In the event
that the Premises are not delivered on or before the Estimated Delivery Date,
for any cause or reason, Landlord, its agents and employees, shall not be liable
or responsible for any damages or liabilities in connection therewith incurred
by Tenant as a result thereof, nor shall the obligations of Tenant provided
herein be excused by reason of any such delay, however, if the failure to
deliver the Premises on the Estimated Delivery Date is due solely to the
unexcused actions of Landlord hereunder (or Landlord's failure to deliver free
of tenants), then, in such event, Tenant's sole right and remedy (subject to
Section 1.04 hereof) shall be to delay the Commencement Date by the number of
days that delivery is delayed solely by the unexcused actions of Landlord, but
in no event shall the Commencement Date be later than the date on which Tenant
takes possession or commences business operations upon the Premises or part
thereof. On or before the Estimated Completion Date, Landlord shall use its best
efforts to substantially complete the Leasehold Improvements to be constructed
or installed by Landlord in the Premises pursuant to Exhibit "B" to this Lease.
In the event that the Leasehold Improvements are not completed on or before the
Estimated Completion Date, for any cause or reason, Landlord, its agents and
employees, shall not be liable or responsible for any damages or liabilities in
connection therewith incurred by Tenant as a result thereof, nor shall the
obligations of Tenant provided herein be excused by reason of any such delay.
The Leasehold Improvements shall be deemed completed upon the date Landlord's
Architect (as defined in Exhibit "B") certifies that the Premises have been
substantially completed, subject to completion of those items, if any, listed on
Landlord's punch list. Nothing herein shall delay or extend the Commencement
Date or the Rent Commencement Date.


         SECTION 1.03. RENTABLE AREA.

         The term "Rentable Area" as used herein means all floor area in the
Building. The Rentable Area of the Premises is approximately stated in the Basic
Lease Information and shall be specifically calculated by Landlord's Architect
in accordance with Building Owners and Managers Association Method of
Measurement 1996 (ANSI/BOMA Z65.1-1996). Upon such determination by Landlord's
Architect, the Rentable Area of the Premises shall be appropriately adjusted, if
necessary, to reflect the number of square feet of Rentable Area of the Premises
as determined by such calculation. Tenant, at its expense, may have the
measurement of the Premises verified by its architect. If Tenant's measurement
shall determine that the measurement of the Premises does not comply with
ANSI/BOMA Z65.1-1996 and if Landlord's Architect concurs with said
determination, then an appropriate adjustment to the Rentable Area of the
Premises shall be made by Landlord. Tenant must notify Landlord of any such
assertion within ninety (90) days after the Commencement Date or Tenant shall be
deemed to have approved the Rentable Area of the Premises and waived its right
to object. The Rentable Area of the Building and the Premises shall be adjusted,
if necessary, by Landlord's Architect in the event of any future expansion or
modification of the Building and/or the Premises. If the number of square feet
of (i) the Rentable Area of the Building, or (ii) the Rentable Area of the
Premises changes, then Tenant's Proportionate Share shall be adjusted effective
as of the date of any such change.


                                      C-1
<PAGE>   21


         SECTION 1.04. TERMINATION DUE TO FAILURE TO DELIVER POSSESSION.

         Notwithstanding any contrary provision contained in Section 1.02
hereof, if Landlord has not tendered possession of the Premises to Tenant within
one hundred twenty (120) days from the Estimated Delivery Date, and such delay
was not the result of either (i) delays caused by force majeure or (ii) Tenant
Delay, or (iii) any act or omission of Tenant or anyone for whom Tenant is
responsible, then Tenant may, at its option, by notice in writing to Landlord
given within thirty (30) days thereafter, cancel this Lease, however, Tenant's
rights under this Section shall terminate in the event that Landlord, prior to
its receipt of Tenant's notice exercising its termination right, has notified
Tenant that the Leasehold Improvements are substantially completed. If Tenant
cancels the Lease, Landlord shall return to Tenant, without interest, the first
installment of Base Rent and the Security Deposit (if previously delivered by
Tenant) and the parties shall be discharged from any and all obligations
hereunder. If Tenant fails to provide Landlord with its notice of election
within the time period specified herein, then Tenant shall be deemed to have
irrevocably waived its rights under this Section 1.04.


         SECTION 1.05. EARLY ENTRY BY TENANT.

         It is acknowledged and agreed that Tenant (and its agents, contractors,
and employees) may enter upon the Premises on the Commencement Date to perform
construction work required by this Lease to be performed by Tenant. Any entry
shall be subject to all of the terms and conditions of this Lease, however,
Tenant's obligations to pay Rent hereunder shall commence on the Rent
Commencement Date. Landlord and Tenant shall cooperate in the scheduling of
their respective work in the Premises so that such work may be completed in a
timely manner.


           PART 2 - ACCEPTANCE OF THE PREMISES AND BUILDING BY TENANT

         Taking possession of the Premises by Tenant shall be conclusive
evidence that Tenant: (i) accepts the Premises as suitable for the purposes for
which they are leased; (ii) accepts the Building and every part and appurtenance
thereof as being in a good and satisfactory condition; and (iii) waives any
defects in the Premises or the Building except for the completion of those
items, if any, on Landlord's punch list or latent defects which reasonably
cannot be discovered by an inspection of the Premises prior to taking
possession. Landlord represents and warrants that as of the Commencement Date
the Base Building and all common areas within the Building shall be in
compliance with all applicable codes and ordinances, including fire and life
safety compliance and the Americans with Disabilities Act.


                               PART 3 - BASE RENT

         SECTION 3.01. BASE RENT.

         Tenant shall pay to Landlord monthly, in advance, without demand, on
the first day of each calendar month, the monthly Base Rent specified in the
Basic Lease Information, subject to adjustment as provided in Section 3.02 of
the General Lease Provisions. The first monthly installment of Base Rent shall
be payable by Tenant on the Rent Commencement Date. If the Rent Commencement
Date is a date other than the first day of a calendar month, then Tenant shall
pay to Landlord on the Rent Commencement Date a prorated installment of Base
Rent for the first fractional month of the Term.


         SECTION 3.02. ADJUSTMENTS TO BASE RENT.

         (a) During the Term and the Renewal Term of this Lease, the Base Rent
shall be adjusted on the first year anniversary of the Rent Commencement Date
and on the first day of each annual anniversary of the Rent Commencement Date
thereafter pursuant to this Section. The dates described in this Section for
computing the adjustment in Base Rent are hereinafter sometimes


                                      C-2
<PAGE>   22


referred to collectively as "Rental Adjustment Dates" and singularly as a
"Rental Adjustment Date". All adjustment to Base Rent required by this Section
3.02 shall be made as hereinafter described:

                  (1) On the first Rental Adjustment Date, the Base Rent shall
be multiplied by the Adjustment Factor and the amount computed shall be added to
the Base Rent as of the first Rental Adjustment Date and the resulting sum shall
be the adjusted rent (hereinafter the "Adjusted Rent") to be paid by the Tenant
to Landlord, in advance, without demand, in equal monthly installments, on the
first day of each calendar month until the next Rental Adjustment Date.

                  (2) On the second Rental Adjustment Date and on every Rental
Adjustment Date throughout the term of this Lease, the Adjusted Rent payable in
the year immediately preceding the Rental Adjustment Date in question shall be
multiplied by the Adjustment Factor and the amount computed shall be added to
the Adjusted Rent for the year immediately preceding the Rental Adjustment Date
and the resulting sum shall be the Adjusted Rent for that rental year to be paid
by the Tenant to Landlord, in advance, without demand, in equal monthly
installments, on the first day of each calendar month until the next Rental
Adjustment Date.

         (b) Landlord shall provide Tenant with written notice of each
adjustment pursuant to Section 3.02(a), which notice shall provide the basis
upon which such adjustment has been calculated; provided, however, that if for
any reason Landlord does not notify Tenant of the amount of such adjustment
until after any Rental Adjustment Date, Tenant shall continue to pay the Base
Rent or Adjusted Rent, as the case may be, payable prior to the Rental
Adjustment Date, and Tenant, within fifteen (15) days following Landlord's
delivery of written notice of such adjustment, shall pay to Landlord in a lump
sum the amount of any increase in the Base Rent resulting from such adjustment
for all months in the existing calendar year prior to and including the month in
which such notice of adjustment is received and during the remainder of such
year Tenant shall pay to Landlord the Adjusted Rent as set forth in such notice.


         SECTION 3.03. PAYMENT.

         All Base Rent, Adjusted Rent and Additional Rent (as hereinafter
defined) shall be paid to Landlord by Tenant when due, without deduction or
offset, in lawful money of the United States, at Landlord's address for Notice
or such other place as Landlord may from time to time designate in writing.


         SECTION 3.04. ACCEPTANCE OF RENT.

         If Landlord shall direct Tenant to pay Base Rent, Adjusted Rent and/or
Additional Rent to a lockbox or other depository whereby checks issued in
payment of Base Rent, Adjusted Rent and/or Additional Rent (or both or all, as
the case may be) are initially cashed or deposited by a person or entity other
than Landlord (albeit on Landlord's authority), and if, for whatever reason,
Landlord does not wish to accept Tenant's payment, then, Landlord shall not be
deemed to have accepted such payment if (and only if) within ten (10) days after
Landlord shall have actually received such funds, Landlord has refunded (or
attempted to refund) such payment to Tenant. Nothing contained in the
immediately preceding sentence shall be construed to place Tenant in default of
Tenant's obligation to pay rent if and for so long as Tenant shall timely pay
the rent required pursuant to this Lease in the manner designated by Landlord.


         SECTION 3.05. SURVIVAL OF RENT OBLIGATION.

         The obligation of Tenant with respect to the payment of past due Base
Rent, Adjusted Rent and Additional Rent shall survive the termination of this
Lease.


                                      C-3
<PAGE>   23


         SECTION 3.06. LATE PAYMENT FEE.

         In the event any installment of Rent due hereunder is not paid within
five (5) calendar days after it is due, then Tenant shall also pay to Landlord
as Additional Rent a late payment fee equal to two percent (2%) of such
delinquent installment of Rent or any component thereof for each and every month
or part thereof that such Rent or any component thereof remains unpaid.


         SECTION 3.07. INTEREST ON PAST DUE RENT.

         All past due installments of Rent shall bear interest until paid at a
rate per annum equal to four percent (4%) above the prime rate of interest from
time to time publicly announced by Bank of America, N.A., or any successor
thereof (the "Default Rate"); provided, however, that if at the time such
interest is sought to be imposed the rate of interest exceeds the maximum rate
permitted under federal law or under the laws of the Commonwealth of Virginia,
the rate of interest shall be the maximum rate of interest then permitted by
applicable law.


                            PART 4 - ADDITIONAL RENT

         SECTION 4.01. OPERATING EXPENSES.

         (a) Throughout the Term, Tenant shall pay on a monthly basis, without
demand, as Additional Rent for the Premises, Tenant's Proportionate Share of the
amount by which Operating Expenses (as defined in Section 4.01(b) hereof) exceed
the Base Operating Expenses Amount. Such payments shall be made as follows:

                  (1) Prior to the Commencement Date and on the first day of
January of each year during the Term, or as soon thereafter as is reasonably
practicable, Landlord shall furnish Tenant with Landlord's estimate of the
Operating Expenses for the forthcoming year. On the first day of each month
during such year, Tenant shall pay one-twelfth (1/12th) of Tenant's
Proportionate Share of the difference between the estimated Operating Expenses
for such year and the Base Operating Expenses Amount. If for any reason Landlord
has not provided Tenant with Landlord's Operating Expenses estimate on or before
the first day of January of any year during the Term (or by the Commencement
Date, as the case may be), then, until the first day of the calendar month
following the month in which Tenant is given Landlord's estimate of Operating
Expenses, Tenant shall continue to pay to Landlord on the first day of each
calendar month the monthly sum payable by Tenant under this Section 4.01 for the
month of December of the preceding year.

                  (2) On the first day of March of each year during the Term, or
as soon thereafter as reasonably practical, Landlord shall furnish to Tenant a
reasonably detailed statement of the actual Operating Expenses for the preceding
year. Within thirty (30) days after the delivery of that statement, a lump sum
payment will be made by Tenant equal to the amount, if any, by which Tenant's
Proportionate Share of the actual Operating Expenses exceeds the amount, if any,
which Tenant has paid toward the estimated Operating Expenses pursuant to
Section 4.01(a)(1) above. If Tenant's Proportionate Share of the actual
Operating Expenses is less than the amount Tenant has paid toward the estimated
Operating Expenses pursuant to Section 4.01(a)(1) above, Landlord shall apply
such amount to the next accruing installments of Rent due hereunder. The
foregoing notwithstanding, Landlord shall have the right from time to time
during any year, but not more frequently than twice in any calendar year, to
notify Tenant in writing of any change in Landlord's estimate of Operating
Expenses for the then current year, in which event Tenant's Proportionate Share
of Operating Expenses, as previously estimated, shall be adjusted to reflect the
amount shown in such notice and shall be effective, and due from Tenant, on the
first day of each month following Landlord's giving of such notice. The effect
of this Section 4.01(a) is that Tenant will pay during each year during the Term
Tenant's Proportionate Share of actual Operating Expenses in excess of the Base
Operating Expenses Amount.

                  (3) If the Commencement Date occurs on a date other than the
first day of January, or if the Term ends on a date other than the last day of
December, the actual Operating Expenses for the year in which the Commencement
Date or the Expiration Date occurs, as the case


                                      C-4
<PAGE>   24


may be, shall be prorated so that Tenant shall pay that portion of Tenant's
Proportionate Share of Operating Expenses for such year represented by a
fraction, the numerator of which shall be the number of days during such
fractional year falling within the Term, and the denominator of which is 365 (or
366, in the case of a leap year). The provisions of this Section 4.01 shall
survive the Expiration Date or any sooner termination provided for in this
Lease.

         (b) As used in this Lease, "Operating Expenses" means all reasonable
expenses, costs, and disbursements of every kind which Landlord incurs, pays or
becomes obligated to pay in connection with the ownership, operation, repair,
and maintenance of the Building, which cost shall include all expenditures by
Landlord to maintain all facilities in operation at the beginning of the Term
and such additional facilities installed in subsequent years as Landlord may
reasonably consider necessary or beneficial for the operation of the Building.
All Operating Expenses shall be determined according to Generally Accepted
Accounting Principles (GAAP) (which shall be consistently applied) and shall
include, but are not limited to, the following:

                  (1) Wages, salaries, and fees of all personnel or entities
(exclusive of Landlord's executive personnel) exclusively (or pro-rate) engaged
in the operation, repair, maintenance, or security of the Building, including
taxes, insurance, and benefits relating thereto;

                  (2) All supplies and materials used in the operation, repair,
security, and maintenance of the Building;

                  (3) Cost of all maintenance and service agreements for the
Building and the equipment therein, including, without limitation, alarm
service, water treatment services, janitorial services, security systems
service, window cleaning, service on electrical and mechanical components, trash
removal, elevator maintenance, extermination service, plumbing service, grounds
keeping, and landscaping;

                  (4) Cost of all insurance relating to the Building for which
Landlord is responsible hereunder, or which Landlord considers reasonably
necessary for the operation of the Building, including, without limitation, the
cost of property, casualty and liability insurance applicable to the Building
and Landlord's personal property used in connection therewith, and the cost of
business interruption or rental insurance in such amounts as will reimburse
Landlord for all losses of earnings and other income attributable to such perils
as are commonly insured against by prudent landlords or required by Landlord's
lender;

                  (5) Cost of repairs and maintenance (excluding repairs and
maintenance paid by proceeds of insurance or by Tenant or other third parties,
and alterations attributable solely to tenants of the Building) of the Building;

                  (6) All utility costs of the Building (exclusive, however, of
such special utility services as described in Part 6 of the General Lease
Provision, the costs of which special utility services shall be payable as
therein provided), including, without limitation, water, power, fuel, heating,
lighting, air conditioning, and ventilating;

                  (7) Amortization of the cost of installation of capital
investment items which are installed primarily to reduce operating costs for the
general benefit of the Building's tenants or to enhance the Building or which
may be required by any governmental authority. All such costs, including
interest costs, shall be amortized over the reasonable life of the capital
investment items, with the reasonable life and amortization schedule being
determined by Landlord according to generally accepted accounting principles,
but in no event to extend beyond the reasonable life of the Building;

                  (8) Landlord's central accounting costs, the cost of an annual
audit and Landlord's legal fees relating to the operation of the Building;

                  (9) A management fee to the manager of the Building not to
exceed three percent (3%) of gross receipts; and


                                      C-5


<PAGE>   25

                  (10) Pro-rata share of Building office rent or rental value
for any central Building management office in the Building or in another
building owned and managed by Landlord or its affiliates.

         (c) Notwithstanding any other provision of this Lease, Operating
Expenses (as defined in Section 4.01(b) above), shall not include, and Landlord
shall be solely liable for, the following expenses:

                  (1) Costs of a capital nature (other than those permitted by
Section 4.01(b)(7) above), including but not limited to, capital improvements,
capital repairs, capital equipment and capital tools, all in accordance with
GAAP;

                  (2) Any costs, fines or penalties incurred due to violations
of any intentional nature by Landlord of any governmental rule or authority;

                  (3) Any and all loss, claim, damage, award, deductibles paid
under any insurance policies or other amount paid or payable by Landlord
(including all attorneys' fees, court costs and other costs incurred in
connection therewith) as a result or arising out of any act of negligence,
breach of contract or willful misconduct by the Landlord or its agents,
employees or contractors to the extent not covered by insurance;

                  (4) Costs incurred for improving, decorating, building-out,
painting or redecorating premises for other tenants in the Building;

                  (5) Marketing, advertising, and promotional expenditures of
any kind with respect to the Building except for those expenses that directly
benefit Tenant; and

                  (6) Leasing commissions, attorneys' fees, cost and
disbursements and other expenses incurred in connection with negotiations or
disputes with present or prospective tenants or other occupants of the Building.


         SECTION 4.02. REAL ESTATE TAXES.

         (a) Throughout the Term, Tenant shall pay on a monthly basis, without
demand, as Additional Rent for the Premises, Tenant's Proportionate Share of the
amount by which Real Estate Taxes (as defined in Section 4.02(c) hereof) exceed
the Base Real Estate Taxes Amount. Such payments shall be made as follows:

                  (1) Prior to the Commencement Date and on the first day of
January of each year during the Term, or as soon thereafter as reasonably
practicable, Landlord shall furnish Tenant with Landlord's estimate of the Real
Estate Taxes for the forthcoming year. On the first day of each month during
such year, Tenant shall pay one-twelfth (1/12th) of Tenant's Proportionate Share
of the difference between the estimated Real Estate Taxes for such year and the
Base Real Estate Taxes. If for any reason Landlord has not provided Tenant with
Landlord's estimate of Real Estate Taxes on or before the first day of January
of any year during the Term (or by the Commencement Date, as the case may be),
then until the first day of the calendar month following the month in which
Tenant is given Landlord's estimate of Real Estate Taxes, Tenant shall continue
to pay to Landlord on the first day of each calendar month the monthly sum
payable by Tenant under this Section 4.02 for the month of December of the
preceding year.

                  (2) On the first day of March of each year during the Term or
as soon thereafter as reasonably practical, Landlord shall furnish to Tenant a
statement of the actual Real Estate Taxes for the preceding year. Within thirty
(30) days after the delivery of that statement, a lump sum payment will be made
by Tenant equal to the amount, if any, by which Tenant's Proportionate Share of
the actual Real Estate Taxes exceeds the amount, if any, which Tenant has paid
toward the estimated Real Estate Taxes pursuant to Section 4.02(a)(1) above. If
Tenant's Proportionate Share of the actual Real Estate Taxes is less than the
amount Tenant has paid toward the estimated Real Estate Taxes pursuant to
Section 4.02(a)(1) above, Landlord shall apply such amount to the next accruing
installment(s) of Rent due hereunder. The foregoing notwithstanding, Landlord
shall have


                                      C-6
<PAGE>   26


the right from time to time during any year, but not more frequently than twice
in any calendar year, to notify Tenant in writing of any change in Landlord's
estimate of Real Estate Taxes for the then current year, in which event Tenant's
Proportionate Share of Real Estate Taxes, as previously estimated, shall be
adjusted to reflect the amount shown in such notice and shall be effective, and
due from Tenant, on the first day of each month following Landlord's giving of
such notice. The effect of this Section 4.02(a) is that Tenant will pay during
each year during the Term Tenant's Proportionate Share of the actual Real Estate
Taxes in excess of the Base Real Estate Taxes.

         (b) If the Commencement Date occurs on a date other than the first day
of January, or if the term ends on a date other than the last day of December,
the actual Real Estate Taxes for the year in which the Commencement Date or the
Expiration Date occurs, as the case may be, shall be prorated so that Tenant
shall pay that portion of Tenant's Proportionate Share of Real Estate Taxes for
such year represented by a fraction, the numerator of which shall be the number
of days during such fractional year falling within the Term, and the denominator
of which is 365 (or 366, in the case of a leap year). The provisions of this
Section 4.02 shall survive the Expiration Date or any sooner termination
provided for in this Lease.

         (c) As used in this Lease, the term "Real Estate Taxes" shall including
the following:

                  (1) All real estate taxes, including general and special
assessments, if any, which are imposed upon Landlord or assessed against the
Building or the land upon which the Building is situated; and

                  (2) Any other present or future taxes or governmental charges
that are imposed upon Landlord, or assessed against the Building or the land
upon which the Building is situated, including, but not limited to, any tax
levied on or measured by the rents payable by tenants of the Building which is
in the nature of, or in substitution for, real estate taxes. Any inheritance,
estate, gift, franchise, corporation, income, or net profits tax which may be
assessed against Landlord and/or the Building shall be excluded.


         SECTION 4.03. PARKING.

         During the Term, Tenant and its employees, invitees, and guests shall
have the right to use free of charge, in common, with the other tenants of the
Building, the parking areas for the Building, all on an unassigned and
unreserved basis. Landlord reserves the right to promulgate reasonable rules and
regulations of general application for the use of all parking spaces.
Notwithstanding the foregoing, throughout the Term, Landlord shall provide
Tenant, free of charge, with ten (10) reserved parking spaces in a location in
the parking area to be reasonably determined by Landlord.


         SECTION 4.04. ADDITIONAL RENT DEFINED.


         The term "Additional Rent" shall include, but not be limited to (i) the
late payment fee, if any, under Section 3.06; (ii) Tenant's Proportionate Share
of Operating Expenses as calculated under Section 4.01; (iii) Tenant's
Proportionate Share of Real Estate Taxes as calculated under Section 4.02; and
(iv) all other costs and expenses which Tenant assumes, agrees or is required to
pay to Landlord pursuant to this Lease. In the event of nonpayment of Additional
Rent, Landlord shall have all the rights and remedies herein provided for in
case of nonpayment of Rent.


         SECTION 4.05. RENT DEFINED.

         The term "Rent" shall include Base Rent, Adjusted Rent and Additional
Rent.


                                      C-7
<PAGE>   27


         SECTION 4.06. AUDIT BY TENANT.

         Tenant may audit Landlord's Operating Expenses and Real Estate Taxes at
Tenant's sole cost and expense, in order to verify the accuracy of the same,
provided that:

                  (i) Tenant may audit the expenses of the prior year by
notifying Landlord, in writing, within ninety (90) days after its receipt of
Landlord's statement of the actual expenses incurred during the preceding
calendar year. Failure to notify Landlord within such period shall be deemed a
waiver of Tenant's right to audit expenses for said year.

                  (ii) Such audit will be conducted only during regular business
hours at the office where Landlord maintains Operating Expenses and Real Estate
Taxes records and only after Tenant gives Landlord fifteen (15) days prior
written notice.

                  (iii) Such audit shall be conducted on a non-contingent fee
basis.

         Tenant shall deliver to Landlord a copy of the results of such audit
within fifteen (15) days of its receipt by Tenant. In the event the audit
determines Tenant has underpaid its share of either the Operating Expenses or
Real Estate Taxes, and if Landlord concedes the accuracy of the audit, Tenant
shall immediately pay to Landlord any amounts which may be owing. In the event
the audit determines that Tenant has overpaid either the Operating Expenses or
Real Estate Taxes, and if Landlord concedes the accuracy of the audit, Landlord
shall grant Tenant a credit for the amount of the overpayment against the next
accruing installments of Rent due hereunder. In the event Tenant's Proportionate
Share of Operating Expenses or Real Estate Taxes has been overstated by Landlord
by more than five percent (5%), and if Landlord concedes the accuracy of the
audit, Landlord shall also reimburse Tenant for the reasonable costs and
expenses of the audit, not to exceed $2,000.00.


                          PART 5 - SERVICES BY LANDLORD

         While Tenant is occupying the Premises and is not in Default under this
Lease, Landlord shall furnish the Premises with: (i) (7 days per week, 24 hours
a day) passenger elevator service in common with other tenants for access to and
from the Premises, provided that Landlord may reasonably limit the number of
elevators to be operated at night after normal business hours and on Saturdays,
Sundays, and holidays and that Landlord may remove elevators from service for
maintenance in a manner designed to reduce interference to the tenants; (ii)
janitorial cleaning services Monday through Friday (except holidays) as
described in Exhibit "F" hereto, subject to modification as required in
Landlord's reasonable judgment; (iii) replacement, as necessary, of all lamps
and ballasts in Building Standard light fixtures within the Premises; and (iv)
the utility services provided for in Part 6 below. If Tenant requires services
which are not specified herein and Landlord elects to provide such services to
Tenant, Tenant will pay to Landlord, upon demand, as Additional Rent, Landlord's
charges for providing such services.

         Failure to furnish, or any stoppage of, the services provided for in
this Part 5 and in Part 6 below resulting from any cause will not make Landlord
liable in any respect for damages to any person, property, or business, nor be
construed as an eviction of Tenant, nor entitle Tenant to any abatement of Rent,
or damages because of malfunctions or any interruptions in service.

         Notwithstanding the foregoing, if such malfunction or interruption in
service is due solely to the negligent act or willful omission of Landlord or
its agents, employees, contractors or representatives, and such malfunction or
interruption in service (i) continues for five (5) consecutive business days and
(ii) makes it reasonably impossible for Tenant's continued use and occupancy of
the Premises (or portion thereof), and (iii) requires Tenant to vacate the
Premises, then Tenant shall be entitled to an abatement of Base Rent and/or
Adjusted Rent for the portion of the Premises vacated for the period commencing
on the date of vacation of the Premises due to the malfunction or interruption
of services, and continuing until the earlier of the following (i) the date such
service is corrected or restored or (ii) the date Tenant reoccupies any part of
the Premises which was vacated because of the interruption in service,
notwithstanding the fact that the malfunction or interruption in service has not
been corrected.

                                      C-8


<PAGE>   28

                               PART 6 - UTILITIES

         SECTION 6.01. COMPUTERIZED ENERGY MANAGEMENT SYSTEM.

         The Building has been designed with a Computerized Energy Management
System (the "CEMS") which controls the heating, ventilating and air conditioning
system (the "HVAC") for the Premises. Tenant will designate to Landlord
authorized representatives of the Tenant who will be given, through the CEMS,
direct control of the HVAC system for use after normal Building hours.


         SECTION 6.02. WATER, HEATING, VENTILATING AND AIR CONDITIONING.


         (a) While Tenant is occupying the Premises and is not in Default under
this Lease, Landlord shall furnish Tenant with the following utilities in the
manner and to the extent customarily provided in office buildings in the
Northern Virginia area: (1) potable water at those points of supply provided
periodically for normal lavatory use by tenants in the Building; (2) heating,
ventilating, and air-conditioning in season on business days from 7:30 a.m. to 6
p.m., and on Saturdays from 8 a.m. to 1 p.m. (except holidays); and (3) electric
lighting for public areas and special service areas of the Building. If Tenant
requires HVAC service outside the hours and days specified above, the additional
service may be requested by use of the CEMS and Tenant will pay for such
services based on measurement from the CEMS at the rate Landlord is then
charging therefor, which rate is currently $30.00 per hour per floor. Landlord
shall have no obligation to provide any additional service to Tenant at any time
Tenant is in Default under this Lease.

         (b) Landlord shall not be liable for its failure to maintain
comfortable atmospheric conditions in all or any portion of the Premises due to
heat generated by any equipment or machinery installed by Tenant (with or
without Landlord's consent) that exceeds generally accepted engineering design
practices for normal office purposes. If Tenant desires additional cooling to
offset excessive heat generated by such equipment or machinery, Landlord will,
upon the written request of Tenant, install supplemental air conditioning units
in the Premises, and the full actual and reasonable cost thereof, including the
cost of installation of unit(s) and meter(s), operation and use, will be paid by
Tenant to Landlord on demand. Tenant will be required to maintain any
supplemental air conditioning units installed pursuant to this Section. Pursuant
to the provisions of this paragraph, Landlord approves Tenant's installation of
a 5-ton supplemental air conditioning unit within the Premises, subject to
approval by Landlord of the final construction drawings and the specifications
for such unit, installation of an electrical meter, and subject to applicable
governmental laws, rules, codes and regulations.


         SECTION 6.03. ELECTRICITY.

         (a) While Tenant is occupying the Premises and is not in Default under
this Lease, Landlord will furnish sufficient power in the Premises twenty-four
hours per day, seven days a week (subject to outages beyond Landlord's control
and reasonable interruptions as may be required from time-to-time for the
maintenance and improvement of the Building and Building systems) for lighting
and for personal desktop computers, a typical network server, typewriters, word
processors, calculating machines, copying machines, and other similar office
equipment of low electrical consumption. Tenant will not install or operate in
the Premises any heavy duty electrical equipment or machinery without first
obtaining prior written consent of Landlord, which approval shall not be
unreasonably withheld, conditioned or delayed. Landlord may require, as a
condition of its consent, for the installation of such equipment or machinery,
payment by Tenant as Additional Rent for excess consumption of electricity that
may be occasioned by the operation of said equipment or machinery. Upon
reasonable prior notice, Landlord may make periodic inspections of the Premises
at reasonable times to determine that Tenant's electrically operated equipment
and machinery complies with the provisions of Part 6.

         (b) If the CEMS reveals that Tenant's use of electricity in the
Premises exceeds by more than ten percent (10%) of the electrical demands on a
square foot basis of other tenants on average


                                      C-9
<PAGE>   29


in the Building, then Tenant shall pay to Landlord (or the utility company if
direct service is provided by such company) promptly upon demand therefore, for
all such excessive electric consumption and demand as shown by the CEMS. Tenant
shall also pay a service charge related thereto as calculated by Landlord.


                                  PART 7 - USE

         The Premises shall be used solely for general office purposes that are
permitted by applicable zoning ordinances and land use requirements and for no
other purpose. Tenant agrees to use and maintain the Premises in a clean,
careful, safe, lawful, and proper manner.


             PART 8 - COMPLIANCE WITH LAWS AND BUILDING REGULATIONS

         SECTION 8.01. COMPLIANCE WITH LAWS.


         Tenant shall, at its sole expense, promptly and faithfully (i) comply
with all present and future laws, ordinances, orders, rules, regulations, and
requirements of every governmental authority having jurisdiction over the
Premises; (ii) comply with the provisions of the Americans with Disabilities Act
42 U.S.C. Section 12101 et seq as it applies to the Premises and Tenant's
activities therein; (iii) comply with any direction made pursuant to law by any
public officers which requires abatement of any nuisance or imposes upon
Landlord or Tenant any duty or obligation arising from Tenant's occupancy or use
of the Premises or from conditions which have been created by or at the
insistence of Tenant; (iv) comply with the requirements of the local board of
fire underwriters, or anybody exercising similar functions with respect to the
construction, care and safety, maintenance and operation of the Premises; and
(v) indemnify Landlord and hold Landlord harmless from any loss, cost, claim, or
expense which Landlord may incur or suffer by reason of Tenant's failure to
comply with its obligations under clauses (i), (ii), (iii) or (iv) above;
provided, however, that nothing herein shall require Tenant to make structural
changes to the Premises unless necessitated by: (i) Tenant's use of the Premises
for purposes other then general office use (however any change of use shall
require Landlord's prior written consent, which may be withheld), (ii) Tenant's
particular manner of use of the Premises, or (iii) other conditions created by
or at the insistence of Tenant. If Tenant receives notice of any such direction
or of violation of any such law, order, ordinance, or regulation, Tenant shall
promptly notify Landlord thereof.


         SECTION 8.02. OBSERVANCE OF BUILDING'S RULES AND REGULATIONS.


         Tenant and its servants, employees, agents, visitors, and licensees
shall observe faithfully and comply strictly with the Rules and Regulations
attached to this Lease as Exhibit "D". Landlord shall at all times have the
right to make reasonable changes in and additions to such Rules and Regulations;
provided Tenant is notified in writing of such changes and that such changes in
existing or new rules and regulations do not materially interfere with the
lawful conduct of Tenant's business in the Premises. Any failure by Landlord to
enforce any of the Rules and Regulations now or hereafter in effect, either
against Tenant or any other tenant in the Building, shall not constitute a
waiver of any such Rules and Regulations. Landlord shall not be liable to Tenant
for the failure or refusal by any other tenant, guest, invitee, visitor, or
occupant of the Building to comply with any of the Rules and Regulations. If
there is any inconsistency between this Lease and the Rules and Regulations set
forth in Exhibit "D" hereto, this Lease shall govern. Landlord shall, however,
enforce the Rules and Regulations in a non-discriminatory manner in what
Landlord reasonably determines in its sole discretion, to be the best interest
of the Building and its tenants.


         SECTION 8.03. HAZARDOUS MATERIALS.


         (a) Except for those materials that are necessary in the normal course
of Tenant's business activities associated with the Permitted Use, Tenant, its
agents, employees, contractors or invites shall not (i) cause or permit any
Hazardous Materials (hereinafter defined) to be brought upon, stored, used or
disposed on, in or about the Premises and/or the Building, or (ii) permit the


                                      C-10
<PAGE>   30


release, discharge, spill or emission of any substance considered to be a
Hazardous Material from the Premises.

         (b) Any Hazardous Materials permitted by subparagraph (a), all
containers therefor, and all materials that have been contaminated by Hazardous
Materials shall be used, kept, stored and disposed of by Tenant in a manner that
shall in all respects comply with all applicable federal, state and local laws,
ordinances, regulations and standards.

         (c) Tenant hereby agrees that it is and shall be fully responsible for
all costs, expenses, damages or liabilities (including, but not limited to those
incurred by Landlord and/or its mortgagee) which may occur from the use,
storage, disposal, release, spill, discharge or emissions of Hazardous Materials
by Tenant whether or not the same may be permitted by this Lease. Tenant shall
defend, indemnify and hold harmless Landlord, its mortgagee and its agents from
and against any claims, demands, administrative orders, judicial orders,
penalties, fines, liabilities, settlements, damages, costs or expenses
(including, without limitation, reasonable attorney and consultant fees, court
costs and litigation expenses) of whatever kind or nature, known or unknown,
contingent or otherwise, arising out of or in any way related to the use,
storage, disposal, release, discharge, spill or emission of any Hazardous
Material by Tenant, its agents, employees, contractors or invites. The
provisions of this Section shall be in addition to any other obligations and
liabilities Tenant may have to Landlord at law or in equity and shall survive
the transactions contemplated herein or any termination of this Lease.

         (d) As used in this Lease, the term "Hazardous Materials" shall
include, without limitation:

              (i) Those substances included within the definitions of "hazardous
substances", "hazardous materials," toxic substances," or "solid waste" in the
Comprehensive Environmental Response Compensation and Liability Act of 1980 (42
U.S.C. Section 9601 et seq.) ("CERCLA"), as amended by Superfund Amendments and
Reauthorization Act of 1986 ("SARA"), the Resource Conservation and Recovery Act
of 1976 ("RCRA"), and the Hazardous Materials Transportation Act, and in the
regulations promulgated pursuant to said laws, all as amended;

              (ii) Those substances listed in the United States Department of
Transportation Table (49 CFR 172.101 and amendments thereto) or by the
Environmental Protection Agency (of any successor agency) as hazardous
substances (40 CFR Part 302 and amendments thereto);

              (iii) Any material, waste or substance which is (A) petroleum, (B)
asbestos, (C) polychlorinated biphenyls, (D) designated as a "hazardous
substance" pursuant to Section 311 of the Clean Water Act, 33 U.S.C.Section 1251
et seq. (33 U.S.C. Section 1321) or listed pursuant to Section of the Clean
Water Act (33 U.S.C. Section 1317); (E) flammable explosives; or (F) radioactive
materials;

              (iv) Those substances regulated pursuant to or identified in the
Virginia Pesticide Law; Air Pollution Control Board; Virginia Waste Management
Act; Environmental Health Service; Transportation of Hazardous Radioactive
Materials; Virginia Hazardous Materials Emergency Response Program; State Water
Control Law; The Groundwater Act of 1973; and Miscellaneous Offenses; and in the
regulations promulgated pursuant to said laws, all as amended; and

              (v) Such other substances, materials and wastes which are or
become regulated as hazardous or toxic under applicable local, state or federal
law, or the United States government, or which are classified as hazardous or
toxic under federal, state, or local laws or regulations.


                              PART 9 - ALTERATIONS

         SECTION 9.01. APPROVAL OF LANDLORD.


         Tenant shall not, at any time during the Term, without Landlord's prior
written consent (except for non-structural cosmetic alterations not visible
outside of the Premises and the total cost which is less than $20,000.00 in any
lease year), make any alterations (structural or otherwise) to


                                      C-11
<PAGE>   31

the Premises. Should Tenant desire any alterations, Tenant agrees to submit all
plans and specifications for same to Landlord for Landlord's written approval,
before beginning such work and Landlord's approval shall not be unreasonably
withheld, conditioned or delayed. Landlord shall not be considered as
unreasonably withholding its approval by refusing to consent to any alterations
which would (i) alter the exterior appearance of the Building, or the public
lobbies, corridors, or common areas thereof; (ii) causes or are likely to cause
any weakening of any part of the structure of the Premises or Building or which
may cause damage or disruption to any Building system; or (iii) violate any
underlying ground lease or deed of trust or mortgage. Upon Tenant's receipt of
Landlord's written approval, Tenant may proceed with the construction of the
approved alterations, but only so long as they are in substantial compliance
with the plans and specifications and provisions of this Part 9. Additionally,
the construction of any alterations, the alterations themselves, or any
maintenance thereof shall comply with all building, safety, fire, plumbing,
electrical and other codes, governmental requirements (including but not limited
to Title III of the Americans with Disabilities Act of 1990, all regulations
issued thereunder and the Accessibility Guidelines for Buildings and Facilities
issued pursuant thereto, as the same are in effect on the date hereof and may be
hereafter modified, amended or supplemented) and insurance requirements, and
shall not require an amount of water, electricity, gas, heat, ventilation, or
air-conditioning which exceeds Building Standard unless prior written
arrangements reasonably satisfactory to Landlord are made with respect thereto.
All alterations desired by Tenant shall be made at Tenant's expense, either by
Tenant's contractors which have been approved in advance by Landlord or, at
Landlord's option, by Landlord's contractors on terms reasonably satisfactory to
Tenant. If the work is performed by Landlord's contractors under Landlord's
supervision, or if Landlord actually supervises the Alterations, Tenant shall
pay to Landlord a fee equal to fifteen percent (15%) of the actual costs of such
work, such fee to cover Landlord's overhead related to the work, including, but
not limited to, Landlord's review of the plans and specifications, coordination
of the work, consultation with professionals regarding the work, and general
administration allocable to the work. All such construction shall be completed
promptly and in a good and workmanlike manner and shall be performed in
compliance with Part 10 hereof.


         SECTION 9.02. OWNERSHIP OF IMPROVEMENTS TO PREMISES.


         At Landlord's election, all leasehold improvements and other principal
alterations to the Premises shall be and remain the Landlord's property, and
shall not be removed from the Premises. If Landlord elects not to acquire
ownership of any such alteration, which election shall be made in writing at the
time such alterations and improvements are approved, and upon the termination of
this Lease Tenant shall, at Tenant's sole expense, cause the same to be removed
and restore the Premises to the condition in which they existed prior to the
alterations. Tenant further agrees to remove, at Tenant's expense, all of its
furniture, furnishings, personal property and movable trade fixtures by the
Expiration Date, and to promptly reimburse Landlord for the actual and
reasonable cost of repairing all damage done to the Premises or the Building by
such removal.


                                 PART 10 - LIENS

         Tenant shall keep the Premises and the Building free from any liens
arising from any work performed, materials furnished, or obligations incurred by
or at the request of Tenant, its agents, employees or independent contractors.
If any lien is filed against the Premises, the Building or Tenant's leasehold
interest therein, which arises out of any purported act or agreement of Tenant,
Tenant shall discharge same within thirty (30) days after its filing, subject to
Tenant's right to contest the same so long as Landlord is fully secured by
depositing with the Landlord at or before commencing said protest an irrevocable
letter of credit payable to Landlord, cash or a bond equal to one hundred
fifteen percent (115%) of the amount claimed to be due. If Tenant fails to
discharge such lien within such period, then, in addition to any other right or
remedy, (i) Landlord may, at its election, discharge the lien by depositing with
a court or a title company, or by bonding, the amount claimed to be due and;
(ii) Tenant shall pay on demand, as Additional Rent, any amount paid by Landlord
for the discharge or satisfaction of any such lien, and all attorney's fees and
other costs and expenses of Landlord reasonably incurred in defending any such
action or in obtaining the discharge of such lien, together with all necessary
disbursements in connection therewith. Further, if Tenant posts a bond, letter
of credit or cash


                                      C-12
<PAGE>   32


with the Landlord, Landlord reserves the right to require or make the payment of
the amount claimed to be due if it is reasonably necessary to prevent a
foreclosure upon the lien.


                                PART 11 - REPAIRS

         SECTION 11.01. TENANT'S OBLIGATIONS.

         Tenant shall keep the Premises and every part thereof in good condition
and repair at all times during the Term and at Tenant's sole cost and expense.
At the end of the Term, Tenant shall surrender to Landlord the Premises and all
alterations, additions, and improvements thereto in the same condition as when
received, subject to the provisions of Part 17 hereof. Landlord shall give
Tenant five (5) days' prior written notice to commence to make repairs, and if
Tenant fails to commence to make such repairs within such time period, Landlord,
at its option, may make such repairs, and Tenant shall pay Landlord, on demand,
Landlord's actual and reasonable costs in making such repairs plus a fee of
fifteen percent (15%) to cover Landlord's overhead, all to constitute Additional
Rent. Landlord has no obligation and has made no promise to alter, remodel,
improve, repair, decorate, or paint the Premises or any part thereof, except as
specifically set forth in this Lease.


         SECTION 11.02. LANDLORD'S OBLIGATIONS.


         Subject to the other provisions of this Lease imposing obligations in
this respect upon Tenant, and subject to the provisions of Parts 13 and 14
hereof, Landlord shall repair, replace, and maintain (a) the external and
structural parts of the Building and the Building systems and (b) all common
areas.


                               PART 12 - INSURANCE

         SECTION 12.01. TENANT'S INSURANCE.

         Tenant, at its sole expense, shall obtain and keep in force the
following insurance:

             (a) Commercial general liability insurance coverage on an
"occurrence basis" against claims for personal injury, including, without
limitation, bodily injury, death, and broad form property damage, in combined
single limits of not less than $1,000,000 per occurrence and a $2,000,000
aggregate, with coverage to include a per location endorsement, contractual
liability, fire legal liability in the amount of $500,000, and other broad form
endorsements that would be carried by a prudent individual conducting a business
similar to Tenant's business. All such insurance policies shall name Tenant as
the named insured thereunder and shall name Landlord and Landlord's mortgagees
as additional insureds thereunder, all as their respective interests may appear;

             (b) Worker's Compensation and Employer's Liability insurance, with
a waiver of subrogation endorsement waiving rights of subrogation against
Landlord, in form and amount satisfactory to Landlord and at a minimum is equal
to that required by the law of Virginia;

             (c) Special Causes of Loss Insurance insuring the Leasehold
Improvements and Tenant's interest in the Premises and all property located in
the Premises, including furniture, equipment fittings, installations, fixtures,
supplies and any other personal property, Leasehold Improvements and alterations
("Tenant's Property"), in an amount equal to the full replacement value, it
being understood that no lack or inadequacy of insurance by Tenant shall in any
event make Landlord subject to any claim by virtue of any theft or loss or
damage to any uninsured or inadequately insured property;

             (d) During the course of construction of any work performed by
Tenant or on Tenant's behalf pursuant to Exhibit "B" or any alterations by
Tenant until completion thereof, Builder's Risk Insurance on a "special causes
of loss" basis (including collapse) on a completed


                                      C-13
<PAGE>   33


value (non-reporting) form for full replacement value covering all work
incorporated in the Building and all materials and equipment in or about the
Premises;

             (e) Auto liability coverage for owned, hired and non-owned vehicles
with a $1,000,000 combined single limit; and

             (f) Excess liability coverage in the amount of $5,000,000 which
will follow form and respond to and increase the limits of the coverages
described in Sections 12.01(a), (b), (c), and (d) above.

         All policies shall be issued by companies having a Best's rating
reasonably acceptable to Landlord and shall be in amounts and in form
satisfactory from time to time to Landlord and Landlord's lender. All policies
shall contain an endorsement or agreement by the insurer that any loss shall be
payable in accordance with the terms of such policy notwithstanding any act or
negligence of Tenant which might otherwise result in a forfeiture of said
insurance, and the further agreement of the insurer waiving all rights of
setoff, counterclaim, or deduction against Tenant. Tenant will deliver
certificates of insurance evidencing each policy to Landlord as soon as
practicable after the placing of the required insurance, but not later than ten
(10) days prior to the date Tenant takes possession of all or any part of the
Premises. All policies shall contain an undertaking by their insurers to notify
Landlord and Landlord's lender in writing, by registered or certified U.S. Mail,
return receipt requested, not less than thirty (30) days before any material
change, reduction in the scope or limits of coverage, cancellation, or other
termination thereof. All policies (except worker's compensation and employer's
liability) shall name Landlord and Landlord's manager as additional insureds and
shall be evidenced as such on a Certificate of Insurance issued to Landlord.

         Landlord reserves the right to periodically review the insurance
coverages required by this Section 12.01 and to revise such requirements to
reflect insurance industry practices or require other forms or amounts of
insurance as may be reasonably required to reflect changes in insurance industry
practices.


         SECTION 12.02. INSURANCE RATING.


         Tenant will not keep, use, sell or offer for sale in, or upon the
Premises any article which may be prohibited by any insurance policy
periodically in force covering the Building and the Leasehold Improvements. If
Tenant's occupancy or business in or on the Premises, whether or not Landlord
has consented to the same, results in any increase in premiums for the insurance
periodically carried by Landlord with respect to the Building or the Leasehold
Improvements, Tenant shall pay any such increase in premiums as Additional Rent
within ten (10) days after being billed therefor by Landlord. As of the date it
executed this Lease, Landlord was not aware of any reason why Tenant's occupancy
or business would cause an increase in premiums.

         If any of the Landlord's insurance policies shall be canceled or
cancellation shall be threatened or the coverage thereunder reduced or
threatened to be reduced in any way because of the use of the Premises or any
part thereof by Tenant or any assignee or subtenant of Tenant or by anyone
Tenant permits on the Premises and, if Tenant fails to remedy the condition
giving rise to such cancellation, threatened cancellation, reduction of
coverage, or threatened reduction of coverage within forty-eight (48) hours
after notice thereof, Landlord may, at its option, either terminate this Lease
or enter upon the Premises and attempt to remedy such condition, and Tenant
shall promptly pay the actual and reasonable cost thereof to Landlord as
Additional Rent. Landlord shall not be liable for any damage or injury caused to
any property of Tenant or of others located on the Premises resulting from such
entry except to the extent caused by the negligence or willful misconduct of
Landlord. If Landlord is unable or elects not to remedy such condition, then
Landlord shall have all of the remedies provided for in this Lease in the event
of a Default by Tenant. Notwithstanding the foregoing provisions of this
Section, if Tenant fails to remedy as aforesaid within any applicable notice and
cure period, Tenant shall be in Default of its obligations hereunder and
Landlord shall have no obligation to remedy such Default.


                                      C-14
<PAGE>   34


         SECTION 12.03. LANDLORD'S INSURANCE.

         Landlord, as part of the Operating Expenses, shall obtain and keep in
force the following insurance:

             (a) Commercial general liability insurance coverage on an
"occurrence basis" against claims in or about the Building (other than the
Premises) for personal injury, including without limitation, bodily injury,
death and broad form property damage, in limits of $1,000,000 per occurrence and
$2,000,000 aggregate;

             (b) Workmen's Compensation and Employer's Liability insurance;

             (c) Special Causes of Loss Insurance insuring the Landlord's
interest in the Building and improvements therein in form satisfactory to
Landlord and in an amount equal to the full replacement value of the Landlord's
insurable interest in the Building;

             (d) Excess liability coverage in the amount of $5,000,000; and

             (e) Any other form or forms of insurance as Landlord, or Landlord's
mortgagees may reasonably require from time to time in form, in amounts, and for
insurance risks against which a prudent Landlord of a comparable size and in a
comparable business would protect itself.

         Promptly after written request by Tenant (but no more frequently than
once each calendar year), Landlord shall deliver Tenant a certificate of
insurance evidencing the above coverages.


         SECTION 12.04. WAIVER OF SUBROGATION.


         All policies covering real or personal property which either party
obtains affecting the Premises shall include, if possible, a clause or
endorsement denying the insurer any rights of subrogation against the other
party to the extent rights have been waived by the insured before the occurrence
of injury or loss, if same are obtainable. Each party waives any rights of
recovery against the other for injury or loss due to hazards covered by policies
of insurance containing such a waiver of subrogation clause or endorsement to
the extent of the injury or loss covered thereby.


                   PART 13 - DAMAGE BY FIRE OR OTHER CASUALTY

         SECTION 13.01. DAMAGE TO PREMISES.


         Tenant shall immediately notify Landlord of any damage to the Building
which affects the Premises. If all or any portion of the Premises are damaged or
destroyed by any casualty against which Tenant is required to be insured under
Section 12.01 of the General Lease Provisions, and if, in Landlord's reasonable
opinion, (i) the Premises cannot be rebuilt or made fit for Tenant's purposes
within one hundred eighty (180) days of the damage or destruction, or (ii) the
proceeds from Tenant's insurance required to be maintained by Tenant pursuant to
Part 12 are insufficient to repair or restore the damage or destruction, then
either Landlord or Tenant shall have the right, at the option of either party,
to terminate this Lease by giving the other, within sixty (60) days after such
damage or destruction, written notice of termination, and thereupon Rent and any
other payments for which Tenant is liable under this Lease shall be apportioned
and paid to the date of such damage, and Tenant shall immediately vacate the
Premises; provided, however, that those provisions of this Lease which are
designated to cover matters of termination and the period thereafter shall
survive the termination hereof.


         SECTION 13.02. DAMAGE TO BUILDING.


         If the Building or any portion thereof is damaged or destroyed by any
cause whatsoever, to the extent that, (a) in Landlord's reasonable judgment, it
would not be economically feasible to


                                      C-15
<PAGE>   35

repair or restore such damage or destruction, or (b) in Landlord's reasonable
judgment, the damage or destruction to the Building cannot be repaired or
restored within three hundred sixty (360) days after such damage or destruction,
Landlord may, at its option, terminate this Lease by giving Tenant notice of
such termination within sixty (60) days after such damage or destruction.


         SECTION 13.03. PARTIAL DAMAGE.

         In the event of partial destruction or damage to the Building or the
Premises which is not subject to Section 13.01 or 13.02, but which renders the
Premises partially, but not wholly untenantable, this Lease shall terminate as
to the portion of the Premises which, in Landlord's reasonable opinion, cannot
be used or occupied by Tenant as a result of such casualty and shall remain in
effect as the remainder of the Premises. Landlord shall in such event, within a
reasonable time after the date of such destruction or damage, subject to Tenant
Delay and to the extent and availability of insurance proceeds, restore the
Premises to as near the same condition as existed prior to such partial damage
or destruction, provided that Tenant pays to Landlord Tenant's insurance
proceeds as required in Section 13.05 of the General Lease Provisions. In no
event shall Rent abate or shall any termination occur if damage to or
destruction of the Premises is the result of either (i) a default by Tenant or
(ii) the negligence or willful act of Tenant, or Tenant's agents, employees,
representatives, contractors, successors or assigns, licensees or invitees.


         SECTION 13.04. DAMAGE DURING LAST YEAR OF TERM.

         If the Building or the Premises or any material portion thereof is
destroyed by fire or other causes at any time during the last year of the Term,
then either Landlord or Tenant shall have the right, at the option of either
party, to terminate this Lease by giving written notice to the other within
sixty (60) days after the date of such destruction.


         SECTION 13.05. NO LANDLORD LIABILITY.

         Landlord shall have no liability to Tenant for inconvenience, loss of
business, or annoyance arising from any repair of any portion of the Premises or
the Building. If Landlord is required by this Lease or by any lender or lessor
of Landlord to repair or if Landlord undertakes to repair, Tenant shall pay to
Landlord that amount of Tenant's insurance proceeds which insures such damage as
a contribution towards such repair, and Landlord shall use reasonable efforts to
have such repairs made promptly and in a manner which will not unnecessarily
interfere with Tenant's occupancy.


         SECTION 13.06. APPORTIONMENT OF RENT.

         In the event of termination of this Lease pursuant to this Part 13,
then all Rent shall be apportioned and paid to the date on which possession is
relinquished or the date of such damage, whichever last occurs, and Tenant shall
immediately vacate the Premises according to such notice of termination;
provided, however, that those provisions of this Lease which are designated to
cover matters of termination and the period thereafter shall survive the
termination hereof.


                             PART 14 - CONDEMNATION

         SECTION 14.01. ENTIRE BUILDING.


         In the event that the whole or substantially the whole of the Building
and/or the Premises are taken or condemned for any public purposes, this Lease
and the leasehold estate created hereby shall cease and terminate as of the date
of such taking.


                                      C-16
<PAGE>   36

         SECTION 14.02. PORTION OF BUILDING.

         In the event that any portion of the Building shall be taken or
condemned for any public purpose (whether or not such taking includes any
portion of the Premises), which taking, in Landlord's sole judgment, shall
interfere materially with Landlord's use and operation of the Building or is
such that Landlord determines that the Building cannot be restored to usefulness
in an economically feasible manner, then Landlord shall have the option to
terminate this Lease, effective as of the date specified by Landlord in its
notice of termination.


         SECTION 14.03. PORTION OF PREMISES.

         In the event that a portion, but less than substantially the whole, of
the Premises should be taken or condemned for any public purpose, then this
Lease shall be terminated as of the date of such taking as to the portion of the
Premises so taken, and, unless Landlord exercises its option to terminate this
Lease pursuant to Section 14.02 above, this Lease shall remain in full force and
effect as to the remainder of the Premises. In such event, the Rent will be
diminished by an amount representing the part of such amounts properly
applicable to the portion of the Premises so taken. Further, in such event
Tenant's Proportionate Share shall be recomputed based upon the remaining
Rentable Area in the Premises and in the Building.


         SECTION 14.04. TERMINATION OF LEASE.

         In the event of the termination or partial termination of this Lease
pursuant to the provisions of this Part 14, this Lease and the Term and the
estate hereby granted shall expire as of the date of such termination in the
same manner and with the same effect as if that were the date set for the normal
expiration of the Term of this Lease, and the Rent shall be apportioned as of
such date.


         SECTION 14.05. LANDLORD'S RIGHT TO AWARD.

         All awards, damages, and other compensation paid by the condemning
authority on account of such taking or condemnation (or sale under threat of
such a taking) shall belong to Landlord, and Tenant hereby assigns to Landlord
all rights to such awards, damages and compensation. Tenant agrees not to make
any claim against Landlord or the condemning authority for any portion of such
award or compensation attributable to damages to the Premises, the value of the
unexpired term of this Lease, the loss of profits or goodwill, leasehold
improvements, or severance damages. Nothing contained herein, however, shall
prevent Tenant from pursuing a separate claim against the condemning authority
for the value of Non-Building Standard Leasehold Improvements paid entirely by
the Tenant, furnishings, equipment, and trade fixtures installed in the Premises
at Tenant's expense and for relocation expenses, provided that such claim does
not in any way diminish the award or compensation payable to or recoverable by
Landlord in connection with such taking or condemnation.


                       PART 15 - ASSIGNMENT AND SUBLETTING

         SECTION 15.01. RIGHTS OF TENANTS.

         (a) Tenant may not sell, assign, transfer, or hypothecate this Lease or
any interest herein (either voluntarily or by operation of law, and including,
if Tenant is a corporation, partnership or limited liability company, the sale
or transfer of a controlling interest in Tenant), or sublet the Premises or any
part thereof without the prior written consent of Landlord, which consent shall
not be unreasonably withheld, conditioned or delayed except as provided herein.
If Tenant should desire to assign this Lease or sublet the Premises (or any part
thereof) and provided that Tenant is not then in Default hereunder, Tenant shall
give Landlord written notice at least forty-five (45) days in advance of the
date on which Tenant desires to make such assignment or sublease. Landlord shall
then have a period of thirty (30) days following receipt of such notice within
which to notify Tenant in writing that Landlord elects:


                                      C-17
<PAGE>   37

                  (1) to permit Tenant to assign or sublet such space, subject,
however, to the subsequent written reasonable approval by Landlord of the
instrument of assignment or sublease as to form and substance and of the
proposed assignee or subtenant;

                  (2) to refuse, in Landlord's reasonable discretion, to consent
to Tenant's assignment or subleasing of such space and to continue this Lease in
full force and effect as to the entire Premises. If Landlord should fail to
notify Tenant in writing of such election within such thirty (30) day period,
Landlord shall be deemed to have elected option (2) above; or

                  (3) in the event Tenant desires to sublease for substantially
all of the remaining Term of the Lease (including any sublease which expires
during the last six (6) months of the Term) to recapture the space so affected
as of the date specified by Tenant in its notice, in which event this Lease
shall be terminated as to such space for a period equal to the term identified
in Tenant's notice to Landlord.

         (b) Except as may be otherwise expressly set forth to the contrary, no
assignment or subletting by Tenant shall relieve Tenant of Tenant's obligations
under this Lease. Any attempted assignment or sublease by Tenant in violation of
the terms and provisions of this Section 15.01 shall be void.

         (c) For the purposes of this Section 15.01, the following shall be
deemed an assignment of this Lease.

                  (1) If Tenant is a corporation, the stock of which is not
listed on a "national securities exchange" (as defined in the Securities Act of
1934), then the sale, issuance or transfer (whether cumulatively or in a single
transaction), of stock by Tenant or the shareholders of record, as of the date
hereof, the result of which either changes or makes possible the change in the
voting control of Tenant; and

                  (2) If Tenant is a joint venture, partnership, limited
liability company or other association (collectively referred to as the
"Partnership"), the sale, issuance or transfer (whether cumulatively or in a
single transaction) of ownership of the entity the result of which changes the
management of the entity or the voting control of the entity.

         (d) Nothing herein shall be deemed to make an initial public offering
of Tenant equivalent to an assignment of this Lease.


         SECTION 15.02. EXCESS RENT.

         If the rent agreed upon between Tenant and its proposed subtenant under
any proposed sublease of the Premises (or any part hereof) is greater than the
Base Rent or Adjusted Rent, as the case may be, that Tenant must pay Landlord
hereunder for that portion of the Premises that is subject to such proposed
sublease, fifty percent (50%) of such excess rent (after Tenant has deducted its
reasonable expenses incurred in procuring said sublease) shall be considered
Additional Rent owed by Tenant to Landlord, and shall be paid by Tenant to
Landlord in the same manner that Tenant pays Rent under this Lease.


         SECTION 15.03. RIGHTS OF LANDLORD.

         Landlord may sell, transfer, assign, and convey, all or any part of the
Building and/or the Land and any and all of its rights under this Lease, and in
the event Landlord assigns its rights under this Lease, Landlord shall be
released from any further obligations hereunder arising or accruing from and
after the effective date of such transfer, and Tenant agrees to look solely to
Landlord's successor in interest for performance of such obligations. Landlord
shall promptly notify Tenant of any such sale, transfer, assignment or
conveyance.


                                      C-18

<PAGE>   38


         SECTION 15.04.  AFFILIATE TRANSFER.

         Notwithstanding the provisions of Section 15.01 hereof, Tenant shall
have the right, without the prior consent of Landlord, to assign its entire
interest in this Lease to an Affiliate (hereinafter defined) so long as (i) the
Affiliate delivers to Landlord, concurrently with such assignment, a fully
executed original of the assignment and an assumption agreement whereby the
Affiliate assumes and agrees to perform, observe and abide by the terms,
conditions, obligations and provisions of this Lease applicable to Tenant and
(ii) the entity remains an Affiliate. Further, Tenant shall also have the right,
without the prior consent of Landlord, to sublet all or any portion of the
Premises to an Affiliate so long as (i) such sublease contains provisions
stating that is subject to and subordinate to this Lease and to all matters to
which this Lease is or shall be subordinate, and (ii) the entity remains an
Affiliate. No subletting or assignment by Tenant made pursuant to this Section
shall relieve Tenant of Tenant's obligations under this Lease. As used herein,
the term Affiliate shall mean and collectively refer to (a) a corporation,
individual or other entity which owns and controls all or a majority of the
voting stock of Tenant (if it is a corporation) or controls the day-to-day
decision making of Tenant (the "Parent"), or (b) a corporation or other entity
in which either the Tenant or its Parent owns and controls all or a majority of
the voting stock or ownership interests of the entity and is able to elect (by
ownership of stock or proxy) the board of directors and the officers of the
corporation, or (c) an Affiliate of the Parent, and/or (d) a successor or
surviving corporation in the event of a merger, takeover or other form of
business acquisition of the Tenant. A transfer permitted under this Section will
be excluded from the provisions of Section 15.02 hereof. Tenant shall have the
right to sublease up to one-half of one floor of the Premises to PowerTrust.com,
Inc., a Delaware corporation ("PowerTrust"), provided that PowerTrust meets the
definition of Affiliate set forth above at the time the sublease is made and
that such sublease satisfies the other requirements set forth in this Section
15.04. The parties agree that the requirement that PowerTrust remain an
Affiliate shall not be violated by a spin-off of PowerTrust. No such sublease to
PowerTrust shall relieve Tenant of Tenant's obligations under this Lease.


                            PART 16 - INDEMNIFICATION

         The Tenant shall indemnify the Landlord and hold the Landlord harmless
from and against all loss or liability for or on account of any injury
(including death) or damage received or sustained by any person or persons
(including the Landlord and any employee, agent or invitee of Landlord or any of
them) to the extent that such loss or liability is caused by reason of a Default
by Tenant hereunder or any negligent act or omission on the part of the Tenant
or any agent, employee, representative, business visitor or invitee of the
Tenant.

         The Landlord shall indemnify the Tenant and hold the Tenant harmless
from and against all loss or liability for or on account of any injury
(including death) or damage received or sustained by any person or persons
(including Tenant or any employee, agent or invitee of the Tenant or any of
them) to the extent that such loss or liability is caused by reason of any
negligent act or omission on the part of Landlord or any agent, employee,
representative or business visitor of Landlord.

         If either Landlord or Tenant (the "Indemnitee") is made a party to any
litigation commenced against the Indemnitee which falls within the scope of the
foregoing indemnities, then the other party (the "Indemnitor") shall pay all
costs and expenses, including reasonable attorneys' fees and court costs,
imposed upon or actually and reasonably incurred by Indemnitee because of any
such litigation, and the amount of such costs and expenses, including reasonable
attorneys' fees and court costs, shall be deemed an obligation owing by
Indemnitor to Indemnitee.


                       PART 17 - SURRENDER OF THE PREMISES

         SECTION 17.01. CONDITION OF PREMISES.

         Upon expiration of the Term or other termination of this Lease for any
cause whatsoever, Tenant shall peacefully vacate the Premises in as good order
and condition as the same were at the


                                      C-19
<PAGE>   39


beginning of the Term or may thereafter have been improved by Landlord or
Tenant, except for reasonable use and wear thereof and damage to the Premises by
fire or other casualty or condemnation.


         SECTION 17.02. TENANT HOLDOVER.

         In the event that Tenant shall not immediately surrender the Premises
on the Expiration Date of the Term, Tenant, at the option of Landlord, shall
become a month-to-month Tenant at one hundred fifty percent (150%) of the Rent
in effect during the last month of the Term and subject to all of the terms,
conditions, covenants and agreements of this Lease. Tenant shall give to
Landlord at least thirty (30) days' written notice of any intention to quit the
Premises during any such holdover tenancy, and Tenant shall be entitled to
thirty (30) days' written notice to quit the Premises during any such holdover
tenancy, unless Tenant is in Default hereunder, in which event Tenant shall not
be entitled to any notice to quit, the usual thirty (30) days' written notice to
quit being hereby expressly waived. Notwithstanding the foregoing provisions of
this Section, in the event that Tenant shall hold over after the expiration of
the Term, then at any time prior to Landlord's acceptance of Rent from Tenant as
a monthly Tenant hereunder, Landlord, at its option, may forthwith re-enter and
take possession of the Premises without process, or by any legal process in
force in the Commonwealth of Virginia. Tenant shall be liable to Landlord for
all damage which Landlord suffers because of any holding over by Tenant, and
Tenant shall indemnify Landlord against all claims made against Landlord
resulting from Landlord's delay in delivering possession of the Premises to any
other Tenant or prospective Tenant.


                         PART 18 - ESTOPPEL CERTIFICATES

         Tenant shall execute and return within ten (10) business days any
certificate or agreement that Landlord may request from time to time, stating
that this Lease is unmodified and in full force and effect, or in full force and
effect as modified, and stating the modification. The certificate also shall
state (i) that all work has been completed, and the work and the Premises are
accepted as satisfactory except for items listed on a punchlist, if any,
attached to such certificate; (ii) the amount of Base Rent and Additional Rent
and the dates on which Rent commenced to accrue and to which the Rent has been
paid in advance, and the amount of any security deposit or prepaid Rent; (iii)
that Tenant is paying Rent on a current basis; (iv) that Tenant is in full and
complete possession of the Premises and doing business; (v) that there is no
present default on the part of Landlord, or attach a memorandum stating any such
instance of default; (vi) that Tenant has not advanced any amounts to or on
behalf of Landlord which have not been reimbursed; (vii) that Tenant has no
rights to setoff and no defense or counterclaim against enforcement of its
obligations under the Lease, including the payment of Rent; (viii) that Tenant
understands that this Lease has been collaterally assigned to Landlord's
mortgagee as security for a loan to Landlord and that Rent may not be prepaid
other than as may be provided for in this Lease nor may this Lease be amended,
modified, or waived so as to have a material impact on the financial obligations
of either Tenant or Landlord without such mortgagee's prior written approval;
(ix) that there are no actions, whether voluntary or otherwise, pending against
Tenant under the bankruptcy laws of the United States or any state thereof; (x)
that Tenant has no other notice of any sale, transfer or assignment of this
Lease or of the Rent; and (xi) any other fact pertaining to Tenant's interest in
this Lease which Landlord, or Landlord's mortgagee, may request. Failure to
deliver the certificate within ten (10) business days shall be conclusive upon
Tenant for the benefit of Landlord and any successor to Landlord that this Lease
is in full force and effect and has not been modified except as may be
represented by the party requesting the certificate. Any such certificate may be
relied upon by any prospective purchaser, any ground lessor, or any beneficiary
under the deed of trust on the Building, the underlying land, or any part
thereof.


                                      C-20
<PAGE>   40


                     PART 19 - SUBORDINATION AND ATTORNMENT

         SECTION 19.01. SUBORDINATION.

         This Lease is subject and subordinate to any deeds of trust or other
security instruments which may from time to time during the Term cover the
Building, the underlying land, or any interest of Landlord therein, and to any
advances made on the security thereof, and to any refinancings, increases,
renewals, modifications, consolidations, replacements, and extensions of any of
such deeds of trust or security instruments. This provision is declared by
Landlord and Tenant to be self-operative and no further instrument shall be
required to effect such subordination of this Lease. Upon demand, however,
Tenant shall execute, acknowledge, and deliver to Landlord any further
instruments and certificates evidencing such subordination as Landlord, or the
holder of any deed of trust covering the Building, the underlying land, or any
interest of Landlord therein, may reasonably require. This Lease is further
subject and subordinate to all ground or primary leases hereafter in existence
and affecting the Building or the underlying land and to any modifications and
extensions thereof.


         SECTION 19.02. ATTORNMENT.

         Notwithstanding the generality of the foregoing provisions of Section
19.01 hereof, any such mortgagee shall have the right, unilaterally, at any time
fully or partially to subordinate any such deeds of trust or other security
instruments to this Lease on such terms and subject to such conditions as such
mortgagee may consider appropriate in its discretion, and upon any request, by
such mortgagee, Tenant shall execute an instrument confirming any such full or
partial subordination by any mortgagee. At any time, before or after the
institution of any proceedings for the foreclosure sale under any deed of trust
or other security instrument, or the conveyance of the Building under any deed
of trust or other security instrument, Tenant shall attorn to the purchaser upon
any such sale or to the grantee under any deed in lieu of foreclosure and shall
recognize such purchaser or grantee as Landlord under this Lease without any
change in the terms or other provisions of this Lease. Tenant hereby waives the
right, if any, to elect to terminate this Lease or to surrender possession of
the Premises in the event of foreclosure of any deed of trust or security
instrument (or any transfer in lieu thereof). The foregoing agreement of Tenant
to attorn shall survive any foreclosure sale or conveyance in lieu thereof.
Tenant shall upon demand at any time, before or after any such foreclosure sale
or conveyance in lieu thereof, execute, acknowledge, and deliver to Landlord's
mortgagee or any successor thereof or any then-owner of the Building any written
instruments and certificates evidencing such attornment as Landlord's mortgagee
may reasonably require.


         SECTION 19.03. NON-DISTURBANCE AGREEMENT.

         Landlord agrees to use commercially reasonable efforts to obtain from
the mortgagee for the existing indebtedness (the "Existing Indebtedness") and in
the event of a future financing (the "New Financing") of the Landlord's interest
in the Building and/or the land upon which the Building is situated a
Subordination, Non-Disturbance and Attornment Agreement on the mortgagee's
standard form which provides that, in the event of a foreclosure or a transfer
in lieu thereof, Tenant will not be disturbed in its possession of the Premises
in accordance with this Lease so long as (i) no Default has occurred on the part
of Tenant under this Lease; and (ii) Tenant attorns to the purchaser or
transferee as landlord under this Lease, in which case this Lease shall,
notwithstanding the foreclosure or transfer in lieu thereof, continue in full
force and effect upon and subject to all terms, covenants, conditions, and
obligations of this Lease.


                            PART 20 - QUIET ENJOYMENT

         Provided Tenant performs all of Tenant's obligations under this Lease,
including the payment of Rent, Tenant shall, during the Term, peaceably and
quietly enjoy the Premises without disturbance from Landlord or any other
persons acting by, through, or under Landlord; subject, however, to (i) the
terms of this Lease; (ii) the deeds of trust, ordinances, restrictive covenants,


                                      C-21
<PAGE>   41

leases, easements, and other agreements or encumbrances now or hereafter
affecting the Building or the land on which the Building is situated; (iii) the
right of Landlord to construct on its property any additional buildings or other
improvements now or hereafter permitted by the governmental authorities having
jurisdiction over Landlord's property; (iv) the right of Landlord to relocate
parking spaces for the Building or for the Premises so long as the relocated
parking area remains reasonably accessible to the Premises, conduct renovations
to the Building or make alterations to the Building so long as Landlord's
exercise of these rights does not substantially interfere with Tenant's use of
the Premises; and (v) the right of the Landlord to enter upon the Premises for
purposes of general inspection or during the final twelve (12) months of the
Term future leasing of the Premises. This covenant and all other covenants of
Landlord in this Lease shall be binding upon Landlord and its successors only
with respect to breaches occurring during its and their respective ownership of
Landlord's interest hereunder.


                         PART 21 - SIGNS AND FURNISHINGS

         SECTION 21.01. SIGNS AND ADVERTISEMENTS.

         No sign, advertisement, or notice referring to Tenant shall be
inscribed, painted, affixed, or otherwise displayed on any part of the exterior
or the interior of the Building, except those installed by Landlord on the
directories and the entrance door to the Premises and such other areas, if any,
as Landlord may determine. If Tenant exhibits or installs any sign,
advertisement or notice not permitted hereunder, Landlord shall have the right
to remove the same at Tenant's expense. Landlord reserves the right to affix,
install, and display signs, advertisements, and notices on any part of the
exterior or interior of the Building.

         Notwithstanding the foregoing, Tenant, at its sole cost and expense,
shall have the non-exclusive right to display a sign on the exterior of the
Building facing the Dulles Toll Road, subject to Landlord's approval, in
accordance with all governmental authorities, so long as Tenant is the largest
or second largest tenant of the Building as determined by the amount of Rentable
Area of the Building leased. Tenant is solely responsible for the maintenance,
repair and replacement of said sign.


         SECTION 21.02. FURNISHINGS.

         Landlord shall have the right to prescribe the weight and position of
safes and other heavy equipment and fixtures, which, if considered necessary by
Landlord, shall be installed in such manner as Landlord directs in order to
distribute their weight adequately. In no event shall Tenant place on any part
of the floor of the Premises a load exceeding 80 pounds per square foot which
such floor was designed to carry and which is allowed by law. Any and all damage
or injury to the Premises or the Building caused by moving such heavy equipment
or fixtures or the same being in or upon the Premises, shall be repaired by and
at the sole cost of Tenant. All furniture, equipment, and other bulky matter of
any description shall be delivered to the Premises only through the designated
service entrance of the Building and the designated service elevator during
normal business hours or as otherwise directed or scheduled by Landlord. All
moving of furniture, equipment, and other materials shall be under the
supervision of Landlord, who shall not, however, be responsible for any damage
to or charges for moving the same, except to the extent caused by the negligence
or willful misconduct of Landlord or its agents, representatives or employees.
Tenant agrees to remove promptly from the sidewalks adjacent to the Building any
of Tenant's furniture, equipment, or other material there delivered or
deposited.


                         PART 22 - DEFAULTS AND REMEDIES

         SECTION 22.01. EVENTS OF DEFAULT.

         The occurrence of any one or more of the following events shall
constitute a Default or an Event of Default under this Lease: (a) if Tenant
fails to pay any Rent hereunder as and when such Rent becomes due and such
failure shall continue for more than five (5) business days after


                                      C-22
<PAGE>   42


Landlord gives Tenant written notice of past due Rent; (b) if Tenant fails to
pay Rent on time more than twice in any period of twelve (12) months,
notwithstanding that such payments have been made within the applicable cure
period; (c) if Tenant permits to be done anything which creates a lien upon the
Premises and fails to discharge, or bond such lien or post such security with
Landlord as is required by Part 10 hereof; (d) if Tenant violates the provisions
of Part 15 hereof by making an unpermitted assignment or sublease; (e) if Tenant
fails to maintain in force all policies of insurance required by this Lease and
any such failure shall continue for more than ten (10) days after Landlord gives
Tenant written notice of such failure; (f) if any petition is filed by or
against Tenant under any present or future section or chapter of the Bankruptcy
Code, or under any similar law or statute of the United States or any state
thereof (which, in the case of an involuntary proceeding, is not discharged,
dismissed, stayed, or vacated, as the case may be, within sixty (60) days of
commencement), or if any order for relief shall be entered against Tenant in any
such proceedings; (g) if Tenant becomes insolvent or makes a transfer in fraud
of creditors or makes an assignment for the benefit of creditors; (h) if a
receiver, custodian, or trustee is appointed for the Premises or for all or
substantially all of the assets of Tenant, which appointment is not vacated
within sixty (60) days following the date of such appointment; (i) if Tenant
fails to perform or observe any other term of this Lease and such failure shall
continue for more than thirty (30) days after Landlord gives Tenant notice of
such failure, or, if such failure cannot be corrected within such thirty (30)
day period, if Tenant does not commence to correct such default within said
thirty (30) day period and thereafter diligently prosecute the correction of
same to completion within a reasonable time and in any event prior to the time
failure to complete such correction could cause Landlord to be subject to
prosecution for violation of any law, rule, ordinance or regulation or causes,
or could cause a default under any deed of trust, mortgage, underlying lease,
tenant lease or other agreement applicable to the Building or the land upon
which it is situated; or (j) if Tenant fails to perform a particular provision
(other than the payment of Rent) of this Lease more than three (3) times in any
period of twelve (12) months, notwithstanding that Tenant has corrected any
previous failures within the applicable cure period.


         SECTION 22.02. REMEDIES.

         Upon the occurrence of any Event of Default, Landlord shall have the
right, at Landlord's option, to terminate this Lease. With or without
terminating this Lease, Landlord may re-enter and take possession of the
Premises and the provisions of this Section 22.02 shall operate as a notice to
quit, any other notice to quit or of Landlord's intention to re-enter the
Premises being hereby expressly waived. If necessary, Landlord may proceed to
recover possession of the Premises under and by virtue of the laws of the
Commonwealth of Virginia or by such other proceedings, including re-entry and
possession, as may be applicable. If Landlord elects to terminate this Lease,
everything contained in this Lease on the part of Landlord to be done and
performed shall cease without prejudice; subject, however, to the right of
Landlord to recover from Tenant all Rent and other sums accrued up to the time
of termination or recovery of possession by Landlord, whichever is later.
Whether or not this Lease is terminated by reason of Tenant's Default, Landlord
shall use commercially reasonable efforts, but shall not be obligated to, relet
the Premises for such rent and upon such terms as are not unreasonable under the
circumstances and, if the entire Rent provided in this Lease plus the costs,
expenses, and damages hereafter described shall not be realized by Landlord,
Tenant shall be liable for all damages sustained by Landlord, including, without
limitation, deficiencies in Base Rent, Adjusted Rent and Additional Rent, the
value of any rent abatement, tenant allowance or other payments made to Tenant,
attorney's fees and expenses reasonably incurred, brokerage fees, and the
expense of placing the Premises in rentable condition comparable to the
condition the Premises were in on the Commencement Date or as subsequently
improved and the expense of making any minor repairs or alterations necessary to
put the Premises in a condition reasonably acceptable to a new tenant. Landlord
shall in no way be responsible or liable for any failure to collect any rent due
and/or accrued from such reletting, to the end and intent that Landlord may
elect to hold Tenant liable for the Base Rent, Adjusted Rent, and Additional
Rent, and any and all other items of cost and expense which Tenant shall have
been obligated to pay throughout the remainder of the Term. Any damages or loss
of rent sustained by Landlord may be recovered by Landlord, at Landlord's
option, at the time of the reletting, or in separate actions, from time to time,
as said damage shall have been made more easily ascertainable by successive
relettings, or, at Landlord's option, may be deferred until the expiration of
the Term, in which event Tenant hereby agrees that the cause of action shall not
be deemed to have accrued until the date of



                                      C-23
<PAGE>   43


Expiration of the Term. The provisions contained in this Section 22.02 shall be
in addition to, and shall not prevent the enforcement of, any claim Landlord may
have against Tenant for anticipatory breach of this Lease.


         SECTION 22.03. REMEDIES CUMULATIVE.

         All rights and remedies of Landlord set forth herein are in addition to
all other rights and remedies available to Landlord at law or in equity. All
rights and remedies available to Landlord hereunder or at law or in equity are
expressly declared to be cumulative. The exercise by Landlord of any such right
or remedy shall not prevent the concurrent or subsequent exercise of any such
right or remedy. No delay in the enforcement or exercise of any such right or
remedy shall constitute a waiver of any Default by Tenant hereunder or of any of
Landlord's rights or remedies in connection therewith. Landlord shall not be
deemed to have waived any Default by Tenant hereunder unless such waiver is set
forth in a written instrument signed by Landlord. If Landlord waives in writing
any Default by Tenant, such waiver shall not be construed as a waiver of any
covenant, condition, or agreement set forth in this Lease except as to the
specific circumstances described in such written waiver.


         SECTION 22.04. NO ACCEPTANCE OR SURRENDER.

         No act or thing done by Landlord or its agents during the Term shall
constitute an acceptance of an attempted surrender of the Premises, and no
agreement to accept a surrender of the Premises shall be valid unless made in
writing and signed by Landlord. No re-entry or taking possession of the Premises
by Landlord shall constitute an election by Landlord to terminate this Lease,
unless a written notice of such intention is given to Tenant. Notwithstanding
any such reletting or re-entry or taking possession, Landlord may at any time
thereafter terminate this Lease for a previous Default. Landlord's acceptance of
Rent following an Event of Default hereunder shall not be construed as a waiver
of such Event of Default. No waiver by Landlord of any breach of this Lease
shall constitute a waiver of any other violation or breach of any of the terms
hereof. Forbearance by Landlord to enforce one or more of the remedies herein
provided upon a breach hereof shall not constitute a waiver of any other breach
of this Lease.


         SECTION 22.05.  CUSTOMS AND PRACTICES.

         No custom or practice which may develop between the parties in the
administration of the terms of this Lease shall be construed to waive or lessen
Landlord's or Tenant's right to insist upon strict performance of the terms of
this Lease.


         SECTION 22.06.  PAYMENT OF TENANT'S OBLIGATIONS BY LANDLORD.

         In the Event of Default, Landlord may, but shall not be required to,
make such payment or do such act required to be performed by Tenant. If Tenant
fails to act and Landlord makes such payment or does such act, all costs and
expenses actually and reasonably incurred by Landlord, plus interest thereon at
the Default Rate from the date paid by Landlord to the date of payment thereof
by Tenant, shall be paid by Tenant to Landlord within ten (10) days of written
demand therefor. The taking of such action by Landlord shall not be considered
as a cure of such Default by Tenant or to prevent Landlord from pursuing any
remedy it is otherwise entitled to in connection with such Default.


         SECTION 22.07. DEFAULT BY LANDLORD.

         Tenant agrees to give written notice of any default by Landlord under
this Lease to any lender of Landlord secured by the Premises upon request
thereof by such lender and a reasonable time within which to cure such default
prior to Tenant taking any action to remedy such default or cancel the Lease.


                                      C-24
<PAGE>   44

                           PART 23 - SECURITY DEPOSIT

         SECTION 23.01. APPLICATION OF SECURITY DEPOSIT.

         Within five (5) business days of the full execution of this Lease,
Tenant shall deliver to Landlord the sum stipulated in the Basic Lease
Information as a Security Deposit. If Tenant fails to timely deliver said
Security Deposit, Landlord shall have the right to terminate this Lease by
notice to Tenant. Landlord shall not be required to maintain such deposit in a
separate account. If the Security Deposit is in the form of cash, it shall
accumulate simple interest for the benefit of Tenant at a rate of three percent
(3%), less any applicable bank fees. In the event that there is an increase in
the Rentable Area of the Premises during the Term, then Tenant, upon demand from
Landlord, shall immediately deposit with Landlord an additional sum of money to
become part of the Security Deposit equal to the product of the square foot
increase in Rentable Area of the Premises times the (i) Base Rent or Adjusted
Rent, as the case may be, or (ii) the Base Rent agreed to by Landlord and Tenant
for such square foot increase, as either (i) or (ii) may be applicable,
calculate on a one (1) month basis. The Security Deposit shall be security for
the performance by Tenant of all of Tenant's obligations, covenants, conditions,
and agreements under this Lease. Within thirty (30) days after the expiration of
the Term, and provided Tenant has vacated the Premises and is not then in
Default hereunder, Landlord shall return the Security Deposit to Tenant, less
such portion thereof as Landlord shall have appropriated to satisfy any Default
by Tenant hereunder. In the event of any Default by Tenant hereunder, Landlord
shall have the right, but shall not be obligated to use, apply or retain all or
any portion of the Security Deposit for (i) the payment of any Base Rent,
Adjusted Rent, Additional Rent or any other sum as to which Tenant is in
Default, (ii) the payment of any amount which Landlord may spend or become
obligated to spend to repair physical damage to the Premises or the Building
pursuant to Part 11 hereof, or (iii) the payment of any amount Landlord may
spend or become obligated to spend or for compensation of Landlord for any
losses incurred by reason of Tenant's Default, including, but not limited to,
any damage or deficiency arising in connection with the reletting of the
Premises. If any portion of the Security Deposit is so used or applied, within
ten (10) business days after written notice to Tenant of such use or
application, Tenant shall deposit with Landlord an amount sufficient to restore
the Security Deposit to its original amount, and Tenant's failure to do so shall
constitute a Default under this Lease.


         SECTION 23.02. TRANSFER OF SECURITY DEPOSIT.

         In the event of the sale or transfer of Landlord's interest in the
Building, Landlord shall have the right to transfer the Security Deposit to the
purchaser or assignee, in which event Tenant shall look only to the new landlord
for the return of the Security Deposit (subject to the provisions of this
Lease), and Landlord shall thereupon be released from all liability to Tenant
for the return of the Security Deposit.


         SECTION 23.03. LETTER OF CREDIT.

         Provided the conditions of this Section 23.03 have been satisfied,
Tenant shall have the right to post a letter of credit in the amount of the
Security Deposit as the Security Deposit. The letter of credit shall (i) be
issued by a federally insured bank having an office in the Washington, D.C.
metropolitan area which bank is reasonably acceptable to Landlord; (ii) be
irrevocable; (iii) authorize the Landlord to draw by its sight draft accompanied
by a certificate by Landlord (or its representative) that Landlord is entitled
to draw upon the same pursuant to provisions of this Lease, and (iv) by its
terms not expire prior to the first year anniversary of the Rent Commencement
Date. At least thirty (30) days prior to the expiration of the Letter of Credit,
Tenant shall deliver to Landlord one of the following (i) cash in an amount
equal to the Security Deposit, (ii) an amendment to the letter of credit
extending the expiry date for an additional year, or (iii) a new letter of
credit complying with the terms of this Section 23.03 which has an expiry date
of at least one year from the date of expiration of the existing letter of
credit. Should Tenant deliver either a new letter of credit or cash in lieu of
the letter of credit, then, Landlord will return the letter of credit to Tenant.
The failure of Tenant to deliver Landlord an extension of the letter


                                      C-25
<PAGE>   45


of credit, a new letter of credit or cash in lieu of the letter of credit, at
least thirty (30) days prior to the expiration of the date of the letter of
credit Landlord is holding as a Security Deposit shall entitle Landlord to draw
upon the letter of credit and hold such proceeds pursuant to the provisions of
Section 23.01 hereof.


         SECTION 23.04. REDUCTION OF SECURITY DEPOSIT.

         Provided that no monetary Event of Default has occurred during the
twelve (12) months prior to each of the following dates, the required Security
Deposit shall be reduced in accordance with the chart listed below. If the
Security Deposit is in the form of cash, then within thirty (30) days of each
date set forth below, Landlord shall return to Landlord such amount, including
any accrued interest, necessary to reduce the Security Deposit to the Adjusted
Security Deposit.

<TABLE>
<CAPTION>
         Effective Date                                     Adjusted Security Deposit
         --------------                                     -------------------------
<S>                                                         <C>
         First anniversary of the Rent Commencement Date            $250,000.00
         Second anniversary of the Rent Commencement Date           $200,000.00
         Third anniversary of the Rent Commencement Date            $150,000.00
         Fourth anniversary of the Rent Commencement Date           $100,000.00
</TABLE>


                 PART 24 - LANDLORD'S LIEN AND SECURITY INTEREST

         Landlord shall have a lien upon, and Tenant hereby grants to Landlord a
security interest in, all personal property and equipment of Tenant located in
the Premises and purchased in whole or in part with the Tenant Allowance
(including, without limitation, the systems furniture and case goods purchased
from Computer Associates), as security for the payment of all Rent and the
performance of all other obligations of Tenant required by this Lease. At any
time after a Default by Tenant hereunder, Landlord may seize and take possession
of any and all such personal property and equipment. If Tenant fails to redeem
the personal property and equipment so seized by payment of all sums then due
and unpaid Landlord under and by virtue of this Lease, Landlord shall have the
right, after twenty (20) days' written notice to Tenant, to sell such personal
property and equipment so seized at public or private sale and upon such terms
and conditions as to Landlord may appear advantageous. After the payment of all
proper charges incident to such sale, the proceeds thereof shall be applied to
the payment of any and all sums due to Landlord pursuant to this Lease. In the
event there shall be any surplus remaining after the payment of all sums due to
Landlord, such surplus shall be held by Landlord and applied in payment of
future Rent as it becomes due, and any surplus remaining after payment of all
such Rent shall be paid over to Tenant. Landlord shall have all of the rights
and remedies of a secured party under the Virginia Uniform Commercial Code, and,
upon request by Landlord, Tenant shall execute and deliver to Landlord a
financing statement in form sufficient to perfect the security interest of
Landlord in the aforementioned property and proceeds thereof. A photographic
reproduction of this Lease shall be sufficient as a financing statement, but
shall be filed as such only in the event Tenant fails to execute and deliver a
financing statement requested by Landlord hereunder within five (5) business
days of such request.


                   PART 25 - ATTORNEYS FEES AND LEGAL EXPENSES

         In any action or proceeding brought by either party against the other
under this Lease, the prevailing party shall be entitled to recover from the
other party reasonable attorneys fees, and other reasonable legal expenses and
court costs incurred by such prevailing party in such action or proceeding as
the court may find to be reasonable.


                                PART 26 - NOTICES

         Any notice, demand, request, consent, approval or other communication
which either party hereto is required or desires to give or make or communicate
to the other shall be in writing and shall be given or made or communicated by
United States registered or certified mail or by any overnight or express mail
service which provide receipts to indicate delivery, addressed to the


                                      C-26
<PAGE>   46


parties hereto at the respective addresses specified in the Basic Lease
Information, or at such other address as they have subsequently specified by
written notice.

         All notices shall be effective upon being deposited in the manner
prescribed above, however, the time period in which a response to such notice
must be given shall commence to run from the date of receipt by the addressee
thereof as shown on the return receipt of the notice. Rejection or other refusal
to accept or the inability to deliver because of changed address of which no
notice was given, shall be deemed to be receipt of the notice as of the date of
such rejection, refusal or inability to deliver.


                             PART 27 - MISCELLANEOUS

         SECTION 27.01. NO PARTNERSHIP.

         Nothing contained in this Lease shall be construed as creating a
partnership or joint venture of or between Landlord and Tenant, or to create any
other relationship between the parties hereto other than that of landlord and
tenant.


         SECTION 27.02. BROKERS.

         Landlord recognizes the Broker as the Broker under this Lease and shall
pay the Broker a commission pursuant to a separate agreement between the Broker
and Landlord, Landlord and Tenant each represent and warrant to the other that,
except as provided above, neither of them has employed or dealt with any broker,
agent or finder in carrying on the negotiations relating to this Lease. In the
event of a breach by a party of their foregoing representation and warranty (the
"Defaulting Party"), the Defaulting Party shall indemnify and hold the other
party harmless from and against any claim or claims, damages or expenses
(including any claims for brokerage or other commissions asserted by any broker,
agent, or finder fees) which may arise as a result of such breach.


         SECTION 27.03. SEVERABILITY.

         Every agreement contained in this Lease is, and shall be construed as,
a separate and independent agreement. If any term of this Lease or the
application thereof to any person or circumstances shall be invalid and
unenforceable, the remainder of this Lease, or the application of such term to
persons or circumstances other than those as to which it is invalid or
unenforceable, shall not be affected.


         SECTION 27.04. TRIAL BY JURY.

         Landlord and Tenant each hereby waive trial by jury in any action,
proceeding or counterclaim brought by either of them against the other in
connection with any matter arising out of or in any way connected with this
Lease, the relationship of Landlord and Tenant hereunder, Tenant's use or
occupancy of the Premises, or any claim of injury or damage.


         SECTION 27.05. FORCE MAJEURE.

         Whenever a period of time is herein prescribed for action to be taken
by a party, the party shall not be liable or responsible for, and there shall be
excluded from the computation for any such period of time, any delays due to
strikes, riots, acts of God, shortages of labor or materials, war, governmental
laws, regulations, or restrictions, or any other cause of any kind whatsoever
which is beyond the reasonable control of the party. However, the failure or
inability to obtain or have funds required for a performance of a party's
obligation shall not be a basis of force majeure. Force Majeure shall not be
applicable to Tenant's obligation to pay Rent hereunder as


                                      C-27
<PAGE>   47

and when it is due and payable. Nor shall Force Majeure modify the rights of
Tenant under Part 8 hereof.


         SECTION 27.06. CAPTIONS.

         The article, part, and section headings contained in this Lease are for
convenience only and shall not enlarge or limit the scope or meaning of the
provisions hereof. Words of any gender used in this Lease shall include any
other gender, and words in the singular number shall be held to include the
plural, unless the context otherwise requires.


         SECTION 27.07. BENEFIT AND BURDEN.

         If there be more than one Tenant or Landlord, the obligations hereunder
imposed upon Tenant or Landlord, as the case may be, shall be joint and several,
and all agreements and covenants herein contained shall be binding upon the
respective heirs, personal representatives, successors, and, to the extent
permitted under this Lease, assigns of the parties hereto.


         SECTION 27.08. NO REPRESENTATIONS BY LANDLORD.

         Neither Landlord nor Landlord's agents or brokers have made any
representations or promises with respect to the Premises or the Building except
as herein expressly set forth and all reliance with respect to any
representations or promises is based solely on those contained herein. No
rights, easements, or licenses are acquired by Tenant under this Lease by
implication or otherwise except as expressly set forth in this Lease.


         SECTION 27.09. ENTIRE AGREEMENT.

         This Lease sets forth entire agreement between the parties and cancels
all prior negotiations, arrangements, brochures, agreements, and understandings,
if any, between Landlord and Tenant regarding the subject matter of this Lease.
No amendment or modification of this Lease shall be binding or valid unless
expressed in a writing executed by both parties hereto.


         SECTION 27.10. NO OFFER.

         The submission of this Lease to Tenant shall not be construed as an
offer, nor shall Tenant have any rights with respect thereto unless Landlord
executes a copy of this Lease and delivers the same to Tenant.


         SECTION 27.11. AUTHORITY.

         If Tenant signs as a corporation, each of the persons executing this
Lease on behalf of Tenant represents and warrants that Tenant is a duly
organized and existing corporation, that Tenant has been and is qualified to do
business in the Commonwealth of Virginia, that the corporation has full right
and authority to enter into this Lease, and that all persons signing on behalf
of the corporation were authorized to do so by appropriate corporate actions. If
Tenant signs as a partnership, trust, or other legal entity, each of the persons
executing this Lease on behalf of Tenant represents and warrants that Tenant has
complied with all applicable laws, rules, and governmental regulations relative
to its right to do business in the Commonwealth of Virginia, that such entity
has the full right and authority to enter into this Lease, and that all persons
signing on behalf of the Tenant were authorized to do so by any and all
necessary or appropriate partnership, trust, or other actions. Each of the
persons executing this Lease on behalf of a Landlord entity represents and
warrants that such entity has complied with all applicable laws, rules, and
governmental regulations relative to its right to do business in the
Commonwealth of Virginia, that such entity has the full


                                      C-28
<PAGE>   48


right and authority to enter into this Lease, and that all persons signing on
behalf of such entity were authorized to do so by any and all necessary or
appropriate partnership, trust, or other actions.


         SECTION 27.12. CHANGES REQUESTED BY LENDER.

         If, in connection with obtaining financing for the Building, any lender
shall request reasonable modifications in this Lease as a condition for such
financing, Tenant will not unreasonably withhold, delay, or defer its consent
thereto, provided such modifications do not increase the obligations of Tenant
hereunder or adversely affect either the leasehold interest hereby created or
Tenant's use and enjoyment of the Premises.


         SECTION 27.13. GOVERNING LAW AND CONSTRUCTION.

         This Lease shall be governed by and construed under the laws of the
Commonwealth of Virginia. This Lease consists of three (3) parts, the Basic
Lease, General Lease Provisions and Exhibits which are to be read together as a
complete integrated document. Printed parts of this Lease shall be as binding on
the parties hereto as other parts hereof. Parts of this Lease which are written
or typewritten shall have no greater force or effect than and shall not control
parts which are printed, but all parts shall be given equal effect. Tenant
declares that Tenant has read and understands all parts of this Lease, including
all printed parts thereof. Should any provision of this Lease require judicial
interpretation, it is agreed that the court interpreting or considering same
shall not apply the presumption that the terms hereof shall be more strictly
construed against a party by reason of the rule or conclusion that a document
should be construed more strictly against the party who itself or through its
agents prepared the same, it being agreed that all parties hereto have
participated in the preparation of this Lease and that each party had full
opportunity to consult with legal counsel of its choice before the execution of
this Lease.


         SECTION 27.14. LANDLORD'S LIABILITY.

         Anything contained in this Lease to the contrary notwithstanding,
Tenant agrees that Tenant shall look solely to the estate and property of
Landlord in the Building and the land upon which is situated for the collection
of any judgment or other judicial process requiring the payment of money by
Landlord for any default or breach by Landlord under this Lease, subject,
however, to the prior rights of any mortgagee or lessor of the Building and land
upon which the Building is situated. No other assets of Landlord or any
partners, shareholders, or other principals of Landlord shall be subject to
levy, execution or other judicial process for the satisfaction of Tenant's
claim.


         SECTION 27.15. USE OF NAME OF BUILDING.

         Tenant shall not, without prior written consent of Landlord, use the
name of the Building for any purpose other than as the address of the business
to be conducted by Tenant on the Premises, and Tenant shall not do or permit the
doing of anything in connection with Tenant's business or advertising which in
the reasonable judgment of Landlord may reflect unfavorably on Landlord or the
Building or confuse or mislead the public as to any apparent connection or
relationship between Tenant and Landlord, the Building or the land upon which it
is situated.


         SECTION 27.16. CHANGES BY LANDLORD.

         Landlord shall have the unrestricted right to make changes to all
portions of the Building, without materially or adversely affecting Tenant's
access to or use of the Premises (of which the Building and land upon which it
is situated are a part) in Landlord's reasonable discretion for the purpose of
improving access of or security to the Building or the flow of pedestrian
vehicular traffic therein. Landlord shall be entitled to change the name or
address of the Building (subject to Landlord's obligation to reimburse Tenant up
to $500 for replacement of Tenant's stationery as provided herein). Landlord
shall have the right to close, from time to time, the common areas of


                                      C-29
<PAGE>   49


the land upon which the Building is situated, for such temporary periods as
Landlord deems legally sufficient to evidence Landlord's ownership and control
thereof and to prevent any claim of adverse possession by, or any implied or
actual dedication to the public or any party other than Landlord.


         SECTION 27.17. TIME OF ESSENCE.

         Time is of the essence in this Lease.


         SECTION 27.18.  SATELLITE DISH.

         (a) Tenant shall have the right, subject to the provisions of this
Section, to install, at its sole cost and expense, upon the roof of the Building
a satellite dish antenna. Tenant shall pay to Landlord, on a monthly basis as
Additional Rent, a fee of $300.00 per month for the use of the roof of the
Building for the antenna. The location of the antenna shall be mutually agreed
upon by Landlord and Tenant prior to the Commencement Date. The size, design,
and appearance of the antenna shall be subject to the approval of all applicable
governmental authorities and Landlord. No roof penetrations shall be permitted
or made.

         (b) In the event that Tenant constructs the antenna then, such
construction shall be subject to all of the provisions of this Lease. Tenant
further agrees that the provisions of Part 9 hereof shall apply to Tenant's use
of the roof for the installation and operation of the antenna. Tenant shall
maintain the antenna and the portion of the roof upon which is situated in a
good, clean and proper condition and will, at the end of the Term, remove the
antenna and will return the building to its original appearance where the
antenna was located subject to Landlord's approval.



                                      C-30
<PAGE>   50


                              EXHIBIT "D" TO LEASE

                                     Between

              FIRST CAMPBELL ASSOCIATES, L.C., LOUDOUN CENTER L.C.,
           FAIRFAX CORNER ASSOCIATES L.C., BLUE RIDGE ASSOCIATES L.C.,
              MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
                           (collectively, "Landlord")

                                       and

                          DIGITAL COMMERCE CORPORATION
                                   ("Tenant")


                              Rules and Regulations


         This Exhibit "D" is attached to and made a part of that Office Lease
Agreement dated January 24, 2000 (the "Lease"), between FIRST CAMPBELL
ASSOCIATES, L.C., LOUDOUN CENTER L.C., FAIRFAX CORNER ASSOCIATES L.C., BLUE
RIDGE ASSOCIATES L.C., MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
(collectively, "Landlord"), and DIGITAL COMMERCE CORPORATION, ("Tenant"). Unless
the context otherwise requires the terms used in this Exhibit that are defined
in the Lease shall have the same meanings as provided in the Lease.

         The following rules and regulations have been formulated for the safety
and well-being of all tenants of the Building and to ensure compliance with
governmental and other requirements. Any continuing violation of these rules and
regulations by Tenant shall constitute a Default by Tenant under the Lease.

         Landlord may, upon request of any Tenant, waive compliance by such
Tenant with any of the following rules and regulations, provided (i) no waiver
shall be effective unless signed by Landlord; (ii) any such waiver shall not
relieve such Tenant from the obligation to comply with such rule or regulation
in the future unless otherwise agreed to by Landlord; (iii) no waiver granted to
any Tenant shall relieve any other tenant from the obligation of complying with
these rules and regulations, unless such other tenant has received a similar
written waiver from Landlord; and (iv) any such waiver by Landlord shall not
relieve Tenant from any liability to Landlord for any loss or damage occasioned
as a result of Tenant's failure to comply with any rule or regulation.

         1. Sidewalks, plaza areas, entrances, courts, elevators, stairways,
corridors and all other public areas of the Building shall not be obstructed or
encumbered by any tenant or used for any purpose other than ingress and egress
to and from the premises of such tenant.

         2. No awnings or other projections shall be attached to the outside
wall or windows of the Building. No curtains, blinds, shades, or screens (other
than those furnished by Landlord as Building Standard) shall be attached to or
hung in, or used in connection with, any window or door of the premises of any
tenant.

         3. No showcases or other articles shall be put in front of or affixed
to any part of the exterior of the Building, nor placed in the corridor, or
other public areas of the Building.

         4. Plumbing fixtures and appliances shall be used only for the purposes
for which they were constructed, and no sweepings, rubbish, rags, or other
substances (including, without limitation, coffee grounds) shall be thrown
therein. The cost of repairing any stoppage or damage resulting from misuse of
such fixtures by a tenant or such tenant's servants, employees, agents,
visitors, or licensees, shall be paid by such tenant.

         5. No tenant shall bring or keep, or permit to be brought or kept, any
inflammable (excluding normal and customary cleaning supplies, and office
supplies, so long as such are


                                       D-1
<PAGE>   51

properly stored and in quantities appropriate for immediate use), combustible,
or explosive fluid, materials, chemical, or substance in or about its premises.

         6. No tenant shall mark, paint, drill into, or in any way deface, any
part of the Building or its premises; provided, however Tenant shall be
permitted to hang or install decorative artworks and/or pictures on the interior
walls of the Premises. No boring, cutting, or stringing of wires shall be
permitted.

         7. No cooking shall be done or permitted in the Building by any tenant,
except for that which is consistent with an employee kitchen within the
premises. No tenant shall cause or permit any unusual or objectionable odors to
emanate from its premises.

         8. Neither the whole nor any part of the premises of any tenant shall
be used for manufacturing, for the storage of merchandise, or for the sale or
exchange of merchandise, goods, or property of any kind.

         9. Tenants shall not construct, maintain, use, or operate within their
respective premises any electrical device, wiring, or apparatus in connection
with a loud-speaker system or other sound system, except as reasonably required
as part of a communication system approved prior to the installation thereof by
Landlord. No such loud-speaker system shall be constructed, maintained, used or
operated outside of the premises.

         10. No tenant shall make, or permit to be made, any unseemly or
disturbing noises or disturb or interfere with other tenants or occupants of the
Building or neighboring buildings whether by the use of any musical instrument,
radio, television, or other audio device, whistling, singing, or in any other
way. Nothing shall be thrown out of any doors, windows, or any passageways.

         11. No additional locks or bolts of any kind shall be placed upon any
of the doors or windows by any tenant, nor shall any changes be made in any
existing locks or the locking mechanisms therein, without Landlord's approval
(which approval shall not be unreasonably withheld, conditioned or delayed). The
doors leading to the corridors or main halls shall be kept closed during
business hours except as they may be used for ingress or egress. Each tenant
shall, upon the termination of its tenancy, restore to Landlord all keys of
offices and storage and toilet rooms either furnished to, or otherwise procured
by, such tenant. In the event of the loss of any keys so furnished, such tenant
shall pay to Landlord the replacement cost thereof.

         12. The normal hours of operation of the Building shall be 7:30 a.m. to
6 p.m. Monday through Friday, and 8 a.m. to 1 p.m. on Saturdays, customary legal
holidays excluded, but Tenant shall have access twenty-four (24) hours a day,
seven (7) days a week.

         13. No tenant shall use or occupy or permit any portion of its premises
to be used or occupied as an employment bureau or for the storage, manufacture,
or sale of liquor, narcotics, or drugs. No tenant shall engage or pay any
employees in the Building, except those actually working for such tenant in the
Building, nor advertise for laborers giving an address at the Building.

         14. Landlord reserves the right to exclude from the Building at all
times any person who is not known or does not properly identify himself to the
Building management or watchman on duty. Landlord may at its option, require all
persons admitted to or leaving the Building between the hours of 6 p.m. and 7:30
a.m., Monday through Friday, and at any hour on Saturdays, Sundays, and legal
holidays, to register. Each Tenant shall be responsible for all persons for whom
it authorizes entry into the Building, and shall be liable to Landlord for all
acts or omissions of such persons.

         15. Each tenant, before closing and leaving its premises at any time,
shall lock all entrance doors and turn off all lights and electrical appliances.

         16. No premises shall be used, or permitted to be used, for lodging or
sleeping or for any immoral or illegal purpose.


                                       D-2
<PAGE>   52

         17. Landlord's employees shall not perform, and shall not be requested
by any tenant to perform, any work outside of their regular duties, unless under
specific instructions from the office of Landlord. The requirements of tenants
will be attended to only upon application to Landlord, and any such special
requirements shall be billed to tenants (and paid when the next installment of
rent is due) in accordance with the schedule of charges maintained by Landlord
from time to time or at such charge as is agreed upon in advance by Landlord and
such tenant.

         18. Canvassing, soliciting, and peddling in the Building are
prohibited, and each tenant shall cooperate in seeking their prevention.

         19. No animals of any kind shall be brought into or kept about the
Building by any tenant.

         20. No vending machines for commercial or public use shall be permitted
to be placed or installed in any part of the Building by any Tenant. Tenant may
have vending machines in kitchen or other non-public areas of the Premises so
long as (i) such machines are not available for use by the general public, (ii)
Landlord has approved such machines and (iii) the machines are not visible to
the exterior of the Premises or the Building. Landlord reserves the right to
place or install vending machines in any of the public areas of the Building.

         21. No plumbing or electrical fixtures shall be installed by any Tenant
without the written consent of Landlord, (which approval shall not be
unreasonably withheld, delayed or conditioned).

         22. Bicycles, motorcycles, or any other type of vehicle shall not be
brought into the lobby or elevators of the Building or into the premises of any
tenant.

         23. Landlord has the right to evacuate the Building in event of
emergency or catastrophe.

         24. Landlord shall have the right, exercisable without notice and
without liability to any tenant, to change the name and street address of the
Building, provided that Landlord shall reimburse Tenant for replacement of its
stationary (not to exceed $500.00).

         25. Landlord reserves the right to rescind any of these Rules and
Regulations and make such other and further rules and regulations as in the
judgment of Landlord shall from time to time be needed for the safety,
protection, care, and cleanliness of the Building, the operation thereof, the
preservation of good order therein, and the protection and comfort of its
tenants, their agents, employees, and invitees, which Rules and Regulation when
made and notice thereof given to a Tenant shall be binding upon him in like
manner as if originally herein prescribed.


                                      D-3
<PAGE>   53


                                   EXHIBIT "E"


                            COMMENCEMENT DATE NOTICE

         THIS COMMENCEMENT DATE NOTICE (the "Commencement Date Notice") is made
and entered into this ____ day of ________________, 2000 by and between FIRST
CAMPBELL ASSOCIATES, L.C., LOUDOUN CENTER L.C., FAIRFAX CORNER ASSOCIATES L.C.,
BLUE RIDGE ASSOCIATES L.C., MIRROR RIDGE ASSOCIATES L.C. AND KING STREET II L.C.
(collectively, "Landlord") and DIGITAL COMMERCE CORPORATION ("Tenant"), wherein
Landlord and Tenant have entered into that certain Lease Agreement dated
September 14, 1998 (the "Lease"). Unless otherwise defined herein, all
capitalized terms used herein shall have the same meaning as described in the
Lease.

                                   WITNESSETH:

         WHEREAS, Landlord and Tenant wish to confirm and memorialize the
Commencement Date, Rent Commencement Date and the Expiration Date as defined in
the Lease, Landlord and Tenant agree as follows:

         1. The Commencement Date as defined in the Lease is established to
_________________________.

         2. The Rent Commencement Date as defined in the Lease is established to
_________________________.

         3. The Expiration Date as defined in the Lease is established to be
_________________________.

         4. The Landlord's work and/or delivery of the Premises as required by
the Lease has been substantially completed.

         5. Tenant has accepted possession of the Premises pursuant to the terms
of the Lease.

         Except as described herein, all terms and conditions of the Lease are
and shall remain in full force and effect.

                                       LANDLORD:

                                       FIRST CAMPBELL ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:  Manager

                                       LOUDOUN CENTER L.C.
                                       a Virginia limited liability company

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:  Manager


                       [Signatures continue on next page.]


<PAGE>   54


                                       FAIRFAX CORNER ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:  Manager

                                       BLUE RIDGE ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:  Manager

                                       MIRROR RIDGE ASSOCIATES L.C.
                                       a Virginia limited liability company

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:  Manager

                                       KING STREET II L.C.
                                       a Virginia limited liability company

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:  Manager

                                       TENANT:

                                       DIGITAL COMMERCE CORPORATION
                                       a Delaware corporation

                                       By:
                                             -----------------------------------
                                       Name:
                                             -----------------------------------
                                       Its:
                                             -----------------------------------



                                      E-2
<PAGE>   55


                              EXHIBIT "F" TO LEASE


                       JANITORIAL CLEANING SPECIFICATIONS


SPECIFICATIONS

AREAS:   The entire Premises, including all office space, entrance lobby(ies),
         basement areas, loading platform(s), receiving areas, landings/steps,
         public halls, stairways, lavatories, passageways and elevator cabs.

PART A - DAILY SERVICES (Excluding Saturdays, Sundays, and Holidays)

1.       Toilet Rooms & Showers

         Rest rooms are to receive complete cleaning and sanitation each night
         according to the specifications listed below:

         a.       Commodes and Urinals: Commodes shall be washed inside and
                  outside including under the lips of each bowl. All seats shall
                  be washed. This work shall be performed using an approved
                  disinfectant cleanser. All bright metal shall be cleaned and
                  dry polished. Deodorant blocks shall not be used in the
                  urinals.

         b.       Washbasins: Washbasins shall be washed inside and outside
                  using an approved disinfectant cleanser. All bright metal
                  fixture units and plumbing shall be dry polished.

         c.       Stall Partitions: All stall partitions shall be damp cleaned
                  using an approved disinfectant cleanser. Special attention
                  shall be given to urinal partitions.

         d.       Entrance Doors: All entrance doors, including stops, jambs,
                  and frames shall be cleaned.

         e.       Mirrors and Lights: All mirrors and lights immediately above
                  mirrors shall be cleaned. Burned out lights shall be reported
                  to the maintenance department.

         f.       Couches and Chairs: Leather or vinyl couches and chairs shall
                  be damp cleaned. All vanity chairs, stools and other furniture
                  shall be treated in a like manner.

         g.       Sanitary Napkin Disposal Containers: All sanitary napkin
                  containers shall be emptied, damp cleaned with an approved
                  disinfectant cleanser and provided with a new paper bag liner
                  daily.

         h.       Installation of Supplies: All supplies (the quality of which
                  is to be approved by Tenant) such as toilet tissue, toilet
                  seat covers, paper towels, liquid hand soap and bar soap is to
                  be replenished. Insure that proper liquid soap is used in
                  dispensers to avoid malfunction (dilute with water if
                  necessary to prevent clogging). Periodically, clean operating
                  mechanisms and replace liquid soap supply in each dispenser to
                  insure proper operation.

         i.       Mosaic Floors: o Pick up loose paper and trash
                                 o Sweep all floors
                                 o Wet mop floors, using a disinfectant cleanser

         j.       Walls: Wash/clean walls around soap dispensers, towel
                  containers, and light switches as required to maintain
                  clean/bright appearance.


<PAGE>   56

         k.       Traps and Floor Drains: Shall be maintained free from odor at
                  all times. Periodically, water shall be poured down through
                  these traps/floor drains to insure vapor seal.

                  NOTE: No harsh or abrasive cleaner shall be used without
                  consulting the Property Manager.

2.       Room Cleaning

         Executive Offices - Private Offices - Semi-Private Offices including
         other work stations and work areas - Reception Areas - Conference Rooms
         - General Offices

         The areas stated above are to receive complete general cleaning daily
         according to the specifications listed below.

         a.       Wastepaper and Trash Containers: All trash containers as
                  designated shall be emptied and returned to original
                  locations. Plastic liners shall be used in trash containers
                  and changed as necessary for appearance and sanitation. Trash
                  containers shall be periodically washed, for appearance and
                  sanitation. All trash collected shall be deposited in exterior
                  bulk trash containers provided by the Property Manager. Doors
                  on these containers shall be kept closed when not in use. Any
                  spills occurring during emptying of trash shall be cleaned up
                  immediately (inside or outside), and related stains shall be
                  washed/shampooed as required.

         b.       Entrances to Executive Offices and Entrances of Office Areas
                  on Various Floors: All glass doors, plate glass side panels
                  and mirrors, including metal frames, stops, jambs shall be
                  cleaned as necessary.

         c.       Ash Trays: All ash trays shall be emptied. Ash trays shall
                  then be wiped clean with a damp cloth to remove stains and
                  odors.

         d.       Desks and Chairs: Wood desks shall be thoroughly dusted with a
                  treated dust cloth and oiled/waxed as required. Metal desks
                  shall be damp wiped as necessary to remove spots and stains,
                  including front and side vertical surfaces. All glass desk
                  tops will be damp cleaned. Papers on desks shall not be
                  disturbed. All chairs shall be dusted or vacuumed from top to
                  bottom, as required.

         e.       File and Storage Cabinets: All file and storage cabinets shall
                  be thoroughly dusted with a treated dust cloth. Cabinets lined
                  in a row shall be dusted along the horizontal and vertical
                  surface of each cabinet. Spill stains shall be damp cleaned
                  when required.

         f.       Tables and Lamps: Tables shall be treated in a like manner as
                  desks. Lamps shall be dusted thoroughly, using a treated dust
                  cloth. When dusting lamp shades, be certain that cloth is not
                  laden with dust. Cloth lamps shades shall be vacuumed with a
                  soft brush type tool.

         g.       Hand Dust/Clean daily the following using a treated dust
                  cloth:
                  o     Window Sills
                  o     Pictures and Frames
                  o     Counters
                  o     Radiator and Fan Coil Unit enclosures
                        (damp clean as required)
                  o     Ledges and Shelves under six feet
                  o     Doors, Jambs and Stops
                        (particularly along top/horizontal surface)
                  o     Pushplates and Kickplates
                  o     Coat rack and trees
                  o     Telephones, all types including office and
                        telephones in booths
                  o     Panel boxes, fire extinguishers and cabinets, and
                        fire hose cabinets/enclosures


                                      F-2
<PAGE>   57

         h.       Vinyl (Resilient) Tile Floors: All resilient tile floors shall
                  be dusted with a treated dust mop. All spillage will be
                  removed, including damp mop cleaning when required. (Spray
                  buff floor, using a commercial floor polishing machine,
                  synthetic fiber pad and an approved acrylic polymer finish as
                  required to maintain gloss.)

         i.       Carpets: All carpets shall be thoroughly vacuumed. Special
                  attention will be paid to all spills, spots and adherents for
                  removal. Spot clean carpeting as required.

         j.       Glass Partitions: All glass partitions will be washed to
                  remove fingermarks and smudges.

3.       Other Cleanable Areas

         Main Entrance Lobby - Elevators - Corridors - Snack Bars - Stairways,
         Landings, Loading Platforms, and Receiving Rooms

         The areas listed above are to receive complete daily cleaning as
         prescribed in paragraphs A 1 and 2 above and specialty cleaning
         according to the specifications listed below.

         a.       Main Entrance Lobby: All hard surface floors shall be
                  thoroughly cleaned and non-slip floor finish applied as
                  necessary. (Spray buff floor, using a commercial floor
                  polishing machines, synthetic fiber pad and an approved
                  acrylic polymer finish as required to maintain gloss.) All
                  entrance door glass shall be cleaned. Area mats shall be
                  removed and thoroughly cleaned and returned to their original
                  location. Carpet areas shall be vacuumed daily and spot
                  cleaned as necessary.

         b.       Elevators: Interior walls and ceilings shall be dusted with a
                  treated dust cloth and spot cleaned as required. All carpets
                  shall be vacuumed daily and stains removed when possible.
                  Telephone boxes shall be checked and cleaned of any
                  trash/ashes, etc.

         c.       Corridors/Snack Bars:

                  1.       Carpeted areas shall be vacuumed daily and all stains
                           removed when possible. Resilient flooring shall be
                           swept and damp mopped to remove spillage. (Spray buff
                           floor, using a commercial floor polishing machine,
                           synthetic fiber pad and an approved acrylic polymer
                           finish as required to maintain gloss.)

                  2.       All refuse, trash and garbage from snack bars and
                           vending machine areas shall be collected and removed
                           from the building. Cans used for collection of food
                           remnants shall be periodically washed inside and out.

         d.       Water Fountains: To insure a clean, health condition at the
                  water fountains, the dispensing area shall be washed, cleaned
                  and polished.

         e.       Stairways: Stair landings and steps shall be swept or
                  vacuumed. Hand railings, ledges, grilles, fire apparatus and
                  doors shall be dusted. Spills shall be wiped up daily. Spray
                  buff resilient flooring as required to maintain gloss.

         f.       Outside Entrances: Landings and steps shall be swept. Both
                  sides of entrance glass shall be cleaned. Kick plates and push
                  bars shall be cleaned and polished.

         g.       Loading Platforms/Receiving Rooms: Loading dock areas,
                  platforms and receiving rooms shall be swept daily and damp
                  mopped as required.


                                      F-3
<PAGE>   58


PART B - WEEKLY SERVICES

1.       Toilet Rooms

         Damp clean and dry polish tile walls.

2.       Room Cleaning

         a.       Vertical Surfaces:

                  1.       Wood wall paneling in Executive Offices shall be
                           dusted using a treated dust cloth.

                  2.       Dust vertical surfaces of cabinets, files, etc.

                  3.       All woodwork, doors, walls (including stairwells)
                           shall be spot cleaned to remove smudges/spills, etc.

         b.       Other:

                  1.       Air conditioning return air grills shall be cleaned
                           (vacuumed if necessary).

                  2.       Vacuum all upholstered furniture and clean any
                           leather furniture with a treated cloth.

3.       Other Cleanable Areas

         Stairways and Landings: All stairways and landings shall be damp mopped
         weekly. Dust light fixtures and exposed pipes in stairwells.

PART C - MONTHLY SERVICES

1.       Toilet Rooms

         Dust all high areas and vacuum exhaust grills.

2.       Room Cleaning

         a.       Vertical surfaces and under surfaces (knee wells, chair rungs,
                  table legs, etc.) shall be thoroughly dusted and all glass in
                  doors, partitions, pictures, and bookcases shall be
                  damp-wiped. Dust walls and horizontal surfaces over six feet
                  high.

         b.       Venetian Blinds: Venetian blinds will be dusted in place with
                  a treated dust cloth or venetian blind tool.

3.       Other Cleanable Areas

         Elevators: Carpet shall be lifted where appropriate, and flooring swept
         and damp mopped.

         Garage and parking facilities shall be maintained in a first class
         manner in accordance with specifications that are provided by Landlord
         and acceptable to Tenant in its reasonable discretion.


                                      F-4