<PAGE>   1





                                                                   EXHIBIT 10.17














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                                                                   EXHIBIT 10.17


                           SEVENTH AMENDMENT TO LEASE


         THIS SEVENTH AMENDMENT TO LEASE (the "Seventh Amendment"), is made this
20 day of January, 1998 by and between STATE OF CALIFORNIA PUBLIC EMPLOYEES'
RETIREMENT SYSTEM (as "Landlord") and BROCK INTERNATIONAL, INC. (as "Tenant").

                              W I T N E S S E T H:

         WHEREAS, Atlanta Overlook Associates #3 ("AOA") and Tenant did enter
into that certain Lease Agreement (the "Original Lease"), dated as of January
30, 1988, for space in that certain building known as "Overlook III" (the
"Building"); and

         WHEREAS, AOA and Tenant did enter into that certain First Amendment of
Office Building Lease (the "First Amendment"), dated as of December 27, 1988;
and

         WHEREAS, Landlord and Tenant did enter into that certain Second
Amendment of Office Building Lease (the "Second Amendment"), dated as of October
2, 1989; and

         WHEREAS, Landlord and Tenant did enter into that certain Third
Amendment of Office Building Lease (the "Third Amendment"), dated as of March
10, 1993; and

         WHEREAS, Landlord and Tenant did enter into that certain Fourth
Amendment of Office Building Lease (the "Fourth Amendment"), dated as of June
24, 1993; and

         WHEREAS, Landlord and Tenant did enter into that certain Fifth
Amendment of Office Building Lease (the "Fifth Amendment"), dated as of March
22, 1994; and

         WHEREAS, Landlord and Tenant did enter into that certain Sixth
Amendment of Office Building Lease (the "Sixth Amendment"), dated as of
September 22, 1994; and

         WHEREAS, Brock Control Systems, Inc. did change its name to Brock
International, Inc. and Brock International, Inc. did assume the obligations of
Brock Control Systems, Inc. under the Original Lease, as amended; and

         WHEREAS, the Original Lease, as modified by the First Amendment, Second
Amendment, Third Amendment, Fourth Amendment, Fifth Amendment, and Sixth
Amendment are sometimes herein referred to as the Lease; and

         WHEREAS, Landlord and Tenant desire to modify and amend the Lease, in
the manner and for the purposes herein set forth.

         NOW, THEREFORE, for and in consideration of the mutual covenants
contained herein, and for Ten and No/100 Dollars ($10.00) and other good and
valuable consideration, paid by the parties hereto to one another, the receipt
and sufficiency of which are hereby acknowledged by the parties hereto, the
parties hereto hereby covenant and agree as follows:


         1. Extension of Lease Term. The Lease Term is hereby extended for
twenty-four (24) months (the "Renewal Term") so that the Lease shall now expire
on October 31, 2000 unless earlier terminated in accordance with the terms
thereof. Any reference in the Lease to the Term shall mean the period ending on
October 31, 2000.


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         2. Base Rent. The Base Rent during the Renewal term, shall be as
follows:

<TABLE>
<CAPTION>
                                                            PER RSF PER
                                                            -----------
                         PERIOD                          ANNUM BASE RENT
                         ------                          ---------------
                  <S>                                    <C>   
                  11/01/98 - 10/31/00                        $22.00
</TABLE>



         Such Base Rent shall be paid by Tenant at the time and in the manner
that Base Rent is paid under the Lease. The aforesaid charges do not include any
other charges which might otherwise be due from Tenant under the terms and
conditions of the Lease.

         3. Reduction of Premises. (a) Effective November 1, 1998, the Premises
will be reduced from 48,350 rentable square feet to 25,216 rentable square feet
(hereinafter referred to as the "Reduced Premises"), which is more particularly
shown as outlined on Exhibit "A" attached hereto and incorporated herein by
reference.

         (b) The Base Rent for the Reduced Premises shall be determined in
accordance with Paragraph 2 above.

         4. Tenant's Share. (a) Tenant's Share as described in Paragraph 1.1.3
of Exhibit "B" of the Fourth Amendment shall be adjusted accordingly and, from
and after November 1, 1998, Tenant's Share shall be (subject to further
adjustments as provided in the Lease) 5.83%.

         5. Escalation. Effective November 1, 1998 Paragraph 3 (Increases in
Operating Costs) of the Fourth Amendment is hereby deleted in its entirety, and
the following paragraphs are inserted in lieu thereof:

                  (i) In addition to the Base Rent, Tenant agrees to pay as
Additional Rent to Landlord, Tenant's Share of Estimated Operating Costs (as
such terms are defined in Exhibit "B" attached to this Seventh Amendment, and by
this reference incorporated herein) in excess of the Operating Costs for the
Building for 1998, on a per square foot per annum basis and adjusted as required
herein (the Initial Operating Costs"), which Additional Rent shall be due in
twelve (12) equal installments in each Lease Year. All subsequent payments of
Tenant's Share of Operating Costs shall be due and payable without demand,
deduction or set off in advance on or before the first day of each month of the
Lease Term. During any Lease Year within the Lease Term that is less than twelve
(12) full months, any amount to be paid with respect to such period shall be
proportionately adjusted based on that portion of the Lease Year that this Lease
is in effect.

                  (ii) On or before December 15 of each Lease Year (or as soon
thereafter as is practical), Landlord shall provide Tenant with Landlord's
estimate of Tenant's Share of Estimated Operating Costs for the following Lease
Year. Beginning on January 1, 1999 and continuing on the first (1st) day of
January each year thereafter, the amount of Tenant's Share of Estimated
Operating Costs shall be adjusted to the amount set forth in Landlord's notice.
As promptly as practicable after the end of each Lease Year, Landlord shall
compute the actual Operating Costs for the previous Lease Year. If Tenant's
Share of the actual Operating Costs is greater than the amount Tenant paid to
Landlord as Tenant's Share of the Estimated Operating Costs for the previous
Lease Year, Tenant shall, within fifteen (15) days after receipt of notice of
Tenant's Share of actual Operating Costs, pay to Landlord as Additional Rent an
amount equal to the difference between Tenant's Share of actual Operating Costs
and Tenant's Share of Estimated Operating Costs. If Tenant's Share of the actual
Operating Costs for any Lease Year is less than the amount Tenant paid to
Landlord as Tenant's Share of Estimated Operating Costs for such Lease Year,
such excess amount shall be applied against the installment of Additional Rent
next coming due until the same has been fully applied.


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<PAGE>   4

         6. Tenant Improvements. (a) Tenant hereby takes and accepts the Reduced
Premises "as is, where is", with no representation or warranty by Landlord as to
the fitness or suitability of the Expansion Space for Tenant's purpose.

         (b) If Tenant desires any additional work in the Reduced Space, then
the work will be provided subject to Landlord's prior consent only, and by
Landlord at Tenant's sole cost and expense. Such amount will be paid to Landlord
within thirty (30) days after demand therefor is made by Landlord. 

         7. Expansion Rights. So long as no event of default on the part of
Tenant then exists, and subject to any other current right to an expansion
option, renewal option, first right to lease or other such right granted to a
tenant of the Building or a tenant of any other building within Overlook prior
to the date this Seventh Amendment is executed, and so long as there is no
sublease of any portion of the Premises or any assignment of the Lease, Landlord
shall not at any time lease the space consisting of approximately 3,277 rentable
square feet on the fifteenth (15th) floor of the Building, (the "Offer Space" as
more particularly described in Exhibit "A"), without first giving notice to
Tenant of the proposed lease with a bona fide prospect of such space (the
"Availability Notice"). Such notice shall contain all of the material, economic
terms of the proposed lease. Tenant must elect to lease the Offer Space, or not
to lease such Offer Space, within five (5) business days of the notice from
Landlord, by giving notice to Landlord of Tenant's intent to exercise this first
right of refusal, on the terms offered to Tenant as specified in Landlord's
notice. If Landlord does not receive such notice from Tenant within said five
(5) business days, Tenant shall be deemed to have elected not to lease the space
in question, Tenant shall have no further rights to said space, and Landlord
shall be free to lease the space to another party.

         (b) Tenant shall have the right to lease the Offer Space offered at the
then prevailing market base rental rate and leasehold improvement allowance as
determined by Landlord in its sole, good faith judgment, and indicated by
Landlord in the Availability Notice. If Tenant elects to exercise this right to
lease, Tenant shall deliver notice of such exercise to Landlord. Upon such
notice by Tenant, Tenant shall be bound to lease said portion of said floor on
the same terms and conditions as under the Lease, but at the rental rate and
other terms as set forth in the Availability Notice. Such lease as to the Offer
Space shall commence on the earlier date to occur of (i) Tenant's occupancy of
the Offer Space in question, or (ii) sixty (60) days from the date of Tenant's
notice to elect to lease such Offer Space.

         8. Brokerage. LASALLE PARTNERS MANAGEMENT LIMITED ("LASALLE") HAS
REPRESENTED LANDLORD IN THIS TRANSACTION AND SHALL BE PAID A COMMISSION BY
LANDLORD IN CONNECTION WITH THIS LEASE UNDER A SEPARATE AGREEMENT. Tenant
warrants that it has had no dealings with any broker or agent in connection with
the negotiation or execution of this Amendment, and Tenant agrees to indemnify
Landlord against all costs, expenses, attorneys' fees or other liability for
commissions or other compensation or charges claimed by any broker or agent
claiming the same by, through or under Tenant.

         9. No Other Modifications. Except as set forth herein to the contrary,
all of the terms and conditions of the Lease shall remain in full force and
effect and shall govern and control Tenant's lease from Landlord of the
Premises. Tenant acknowledges and agrees that the Lease is in full effect in
accordance with its terms.

         10. Transfers, Successors and Assigns. This Seventh Amendment shall
inure to the benefit of and shall be binding upon Landlord, Tenant and their
respective transfers, successors and assigns.

         11. Georgia Law. This Seventh Amendment shall be construed and
interpreted under and pursuant to the laws of the State of Georgia.

         12. Exhibit. This Seventh Amendment includes Exhibit "A" and Exhibit
"B" (three pages, attached).


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IN WITNESS WHEREOF, the undersigned have caused this Seventh Amendment to be
executed under seal and delivered on the date and year first above written.

                             "LANDLORD"

                             State of California Public Employees' Retirement
                             System, an agency of the State of California

                             By:  LaSalle Advisors Limited, its Agent

                             By:  
                                  ---------------------------------------------

                             "TENANT"

                             Brock International, Inc.

                             By:  
                                  ---------------------------------------------

                                      its: 
                                            -----------------------------------
                             Attest: 
                                    -------------------------------------------

                                      its: 
                                            -----------------------------------




                                               (CORPORATE SEAL)


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                                   EXHIBIT "A"

                          Attached to and made part of

                     Lease Agreement dated: January 20, 1998

        Landlord: State of California Public Employees' Retirement System

                         Tenant: Brock International, Inc.    


                                                        "Reduced Premises"
                                                           25,216 RSF    
                                                             
                                              
                                              


             OVERLOOK III
             ------------
             10th Floor
            


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                                             "Offer Space"
                                               3,277 RSF
                               
                   
                   OVERLOOK III
                   ------------
                   15 Floor

            
            
            


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                                  Exhibit "B"

                          Attached to and made part of

                     Lease Amendment dated: January 20, 1998

        Landlord: State of California Public Employees' Retirement System
                        Tenant: Brock International, Inc.


1.  Reimbursement for Operating Costs.

1.1 Definitions. The definitions set forth in this Section 1.1 shall be applied
whenever any of the following terms are used in this Special Stipulation 1.

           1.1.1 Operating Costs: shall mean all costs paid by Landlord or its
         representatives in connection with the ownership, management,
         maintenance, operation, leasing, insuring, repairing, redecorating,
         cleaning and securing of the Building, as determined by Landlord to be
         necessary or appropriate, including, without limitation, all of the
         following costs:

                  1.1.1.1 All wages, salaries, commissions and related expenses
                  of all on-site and off-site agents, employees and contractors
                  engaged in the management, operation, maintenance, repair,
                  redecoration, cleaning, and security of the Building, plus the
                  costs of all management, maintenance, and security offices in
                  the Building.

                  1.1.1.2 All supplies and materials used and labor charges
                  incurred in the management, operation, maintenance, repair,
                  redecoration, cleaning and security of the Building.

                  1.1.1.3 All reasonable, non-capital equipment purchased or
                  leased for the performance of Landlord's obligations
                  hereunder.

                  1.1.1.4 All management, maintenance, cleaning, security,
                  advertising, promotional and other service agreements for the
                  Building and the equipment therein, including, without
                  limitation, alarm service, security service, window cleaning,
                  and elevator and escalator maintenance.

                  1.1.1.5 All accounting, legal and engineering fees and
                  expenses, including, without limitation, the cost of audits by
                  certified public accountants.

                  1.1.1.6 All insurance premiums, including, without limitation,
                  fire, casualty, extended coverage, public liability, rent
                  abatement, boiler, and worker's compensation insurance
                  applicable to the Building, Landlord's employees and
                  Landlord's personal property used in connection therewith.

                  1.1.1.7 All redecorating (including painting, wallpapering and
                  floor covering), maintaining and repairing of the Building,
                  structural or non-structural, including, without limitation,
                  the mechanical, electrical, heating, ventilating and air
                  conditioning equipment, landscape maintenance and the
                  replacement of trees and shrubbery (excluding any such cost
                  billed to and paid by individual tenants).

                  1.1.1.8 All removing of trash, rubbish, garbage and other
                  refuse from the Building, as well as removal of ice and snow
                  from the sidewalks, driveways and parking lots.

                  1.1.1.9 All amortization of capital improvements (including
                  accounting, legal, architectural and engineering fees incurred
                  in connection therewith) made to the Building subsequent to
                  the Commencement Date which (i) will improve operating


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<PAGE>   9
 
                  efficiencies; (ii) may be required by any law; or (iii)
                  improve or enhance the health of persons in the Building or
                  safety of the Building.


                  1.1.1.10 All charges for electricity, gas, water, sewer, and
                  other utilities furnished to or services or privileges made
                  available to users of the Building.

                  1.1.1.11 All ad valorem property taxes covering all real and
                  personal property constituting a part of the Building,
                  including, but not limited to, all general and special
                  assessments of every kind.

                  1.1.1.12 Any costs incurred in connection with, as a part of
                  or as a result of the testing of indoor air quality in any
                  portion of the Building.

                  1.1.1.13 All other expenses of owning, maintaining, operating,
                  insuring, securing, managing, cleaning, redecorating or
                  repairing the Building.

                  1.1.2    Notwithstanding any of the foregoing to the contrary,
                           Operating Costs shall not include:

                  1.1.2.1 Costs which are directly reimbursed to Landlord by
                  other tenants.

                  1.1.2.2 Payments on mortgages or ground leases owed by
                  Landlord.

                  1.1.2.3 Costs of leasehold improvements for which Landlord has
                  agreed to pay.

                  1.1.2.4 Payment of any return on equity to any owner of the
                  Building.

                  1.1.2.5  Costs reimbursed by proceeds of insurance.

                  1.1.2.6 Costs of the initial construction of the Building or
                  any depreciation thereof.

                  1.1.2.7 Payments of claims, damages or expenses resulting from
                  any willful is conduct of Landlord or any of its authorized
                  representatives.

                  1.1.2.8 Costs of any tenant improvements or other improvements
                  or other services or other Operating Costs which are performed
                  by or incurred by Landlord for the benefit of a single tenant
                  rather than for the benefit of all tenants of the Building.


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