<PAGE>   1


                                                                   EXHIBIT 10.20


                                     LEASE

         1.      PARTIES:  This lease is made and effective as of July 8, 1992,
by and between HORIZON ASSOCIATES JOINT VENTURE, (hereinafter "Landlord"), and
ROSS WHITE ENTERPRISES, INC., d/b/a NATIONAL COMPUTER DISTRIBUTORS, 
(hereinafter "Tenant").

         2.      PROPERTY: Landlord hereby leases to Tenant and Tenant hereby
takes from Landlord, Suite 700 located on the seventh floor at 6100 Hollywood
Boulevard, Hollywood, Florida 33024, for the term and subject to the provisions
of this lease, being 15,887 rentable square feet, and 15,251 usable square
feet, together with all fixtures, equipment, improvements, installations and
appurtenances which at the commencement of, or during the term of this lease,
are attached thereto, referred to as "Premises" and shown on the floor plan
attached as Exhibit "A", in the building occupying the land described as Parcel
"A" of Development East Plat, Plat Book 122, page 23, Broward County Public
Records.  The building and land are sometimes collectively referred to as the
property.

         3.      TERM:
                 (a)      The initial term of this lease is five (5) years.
The targeted commencement date is September 1, 1992.  However, if the actual
commencement date, as defined in 3(b) below, does not occur by October 31,
1992, then and in that event, Tenant shall have the option to defer occupancy
until February 1, 1993.  If the actual commencement date does not occur by
February 1, 1993, Tenant shall have the option to cancel this lease.  Tenant
shall have five options to extend the lease for two year periods upon the terms
set forth in Article 4. Tenant will provide Landlord, in writing, with ninety
(90) days notification prior to expiration of the initial term (or prior to the
expiration of the then-current renewal term) of its intent to exercise the
initial renewal option, or subsequent renewal option(s), as the case may be.

                 (b)      The actual commencement date shall be the earliest of
(i) the date a certificate of occupancy for the Premises is issued, and
Landlord has substantially performed the work set forth on Exhibit "C", except
that unfinished items of a minor, decorative nature shall not constitute
noncompliance by Landlord, or (ii) the date Tenant first occupies the Premises.
Notwithstanding the foregoing, if the premises are ready, or a certificate of
occupancy is issued prior to September 1, 1992, Tenant shall not be obligated
to occupy the premises until September 1, 1992.

                 (c)      For purposes of determining the date when the
Premises are ready for occupancy, there shall not be considered the duration of
any delay caused by: (i) changes in the work to be performed by Landlord, which
changes have been requested by Tenant after the approval by Landlord and Tenant
of "Tenant Construction Plans" as hereinafter defined; (ii) delays, not caused
by Landlord either directly or indirectly, in furnishing materials or procuring
labor required by Tenant for installations or work in the Premises which are
not encompassed within standard Tenant work, as hereinafter defined; (iii) or
(iv) the performance of any work or activity in the premises by Tenant or any
of its employees, agents or contractors.  The Premises shall be deemed ready
for occupancy, and rent shall be due from the date the Premises would have been
ready, but for the causes described in this subparagraph (c).

                 (d)      When the actual commencement date is established,
Landlord and Tenant shall promptly sign the memorandum of commencement and
expiration dates attached as Exhibit "B".

         4.      BASE RENT; ANNUAL OPERATING COSTS; LEASE TAX; SECURITY
DEPOSIT; SUMMARIES:

                 (a)      Payment: Tenant shall pay to Landlord at 6100
Hollywood Boulevard, Suite 206, Hollywood, Florida 33024, as rent under this
lease, the total of (i) base rent (as defined in Article 4(b)); (ii) Tenant's
proportionate share of annual operating costs (as defined in Articles 4(c) and
4(d)); and (iii) all other sums payable by Tenant to Landlord pursuant to the
provisions of this lease.  The amounts due and payable under subparagraph (d)
are deemed "Additional Rent," and collectively with the "Base Rent," are
hereinafter referred to as "Rent."



                                    1 of 12
<PAGE>   2


         (b)     BASE RENT: The base rent shall be $7.10 per square foot,
during the initial five (5) year term hereof; $10.00 per square foot during the
sixth year, if the first renewal option is exercised; $10.50 per square foot
during the seventh year, if the first renewal option is exercised; $11.02 per
square foot during the eighth year, if the second renewal option is exercised;
$11.57 per square foot during the ninth year if the second renewal option is
exercised; $12.14 per square foot during the tenth year, if the third renewal
option is exercised; $12.74 per square foot during the eleventh year, if the
third renewal option is exercised; $13.37 per square foot during the twelfth
year, if the fourth renewal option is exercised; $14.03 per square foot during
the thirteenth year, if the fourth renewal option is exercised; $14.73 per
square foot during the fourteenth year, if the fifth renewal option is
exercised; and $15.46 per year during the fifteenth year, if the fifth renewal
option is exercised.

                 (i)      intentionally omitted.

                 (ii)     intentionally omitted.

                 (iii)    If the term begins on a day other than September 1,
1992, Base Rent from the actual commencement date until the first day of the
following month shall be prorated.

         (c)     TENANT'S PROPORTIONATE SHARE: The square footage of the
Premises is deemed to be 15,887 rentable square feet.  The square footage of
the building is deemed to be 97,000 square feet, and Tenant's proportionate
share refers to the percentage relationship between the foregoing, namely
16.38%. It is understood, however, that if the size of the building is
increased, if other buildings are erected on the Property, or if any other
event occurs which would decrease Tenant's proportionate share, such event will
be reflected in the above calculation.  In no event may Tenant's proportionate
share be increased.

         (d)     ANNUAL OPERATING COSTS:

                 (i)      For and during the first two years of this lease,
Tenant shall only pay at the rate of $5.50 per square foot, as and for Tenant's
total obligation for its proportionate share of annual operating costs, despite
the fact that Tenant's actual share of annual operating costs may exceed $5.50
per square foot.  Attached as Exhibit "E" is Landlord's supporting
documentation as to this $5.50 per square foot figure.

                 (ii)     The term "Annual Operating Costs" means the actual
costs to Landlord of operating and maintaining the Property including, without
limitation, all improvements thereto, and fixtures and equipment thereon during
each year of this lease (and any renewals or extensions thereof), including
1992.  Such costs include, by way of example rather than of limitation, (1)
charges and fees for, and taxes on water, sewer and electricity, (2) elevator
service, janitorial service, trash removal, cleaning, restriping, maintaining
and repairing all walkways, roadways, and parking areas; and maintenance of all
landscaped areas; (3) charges for required governmental permits; (4) wages,
salaries and benefits of employees of Landlord or any management company
engaged by Landlord, excluding executives and managerial employees of such
entities, in connection with the building; (5) the cost of premiums for hazard,
liability, workers' compensation and other insurance upon the property,
excluding premium increases caused by hazardous or other unusual use of the
property by other tenants or Landlord; (6) service contracts with independent
contractors; (7) professional fees including legal and accounting fees; (8)
repairs, replacements and improvements to the property which are appropriate
for the continued operation of the building as a first class office building;
(9) all real estate taxes and assessments (other than lease taxes as defined in
Article 4(f) of this lease); and (10) the cost of all other items which, under
standard accounting practices, constitute operating or maintenance costs which
are attributable to the property.  The term Annual Operating Costs shall not
include: (a) debt service on the acquisition costs of the building, parking and
other common facilities; (b) capital expenditures for expansion of the
building, parking or other common facilities; (c) capital expenditures for
replacement of original building systems (including heating, air conditioning,
ventilation, electrical plumbing, mechanical and elevators), except to



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<PAGE>   3

the extent intended and resulting in verifiable reductions in the cost of
operating the building, parking and other common facilities; (d) capital
expenditures for remodeling or refurbishment of the building, parking and other
common facilities, to a materially higher standard than existed as of the date
of this lease; (e) Landlord's financing costs, including interest, points and
other forms of loan fees; (f) expenditures by Landlord for tenant improvements;
(g) disproportionate usage of utilities or wear and tear to common facilities
by other tenants (h) legal expenses in connection with matters not related to
the administrative responsibilities of Landlord under this lease; and (i)
depreciation on the building or equipment; income taxes, salaries of Landlord's
officers; and commissions payable to brokers.

                 (iii)    As of December 31 of the third year of this lease
(i.e. December 31, 1994), (and as of December 31 of every year thereafter), or
as soon after December 31 as is possible, Landlord shall compute and provide
Tenant with a statement of the actual annual operating costs for the third year
of this lease (and for subsequent years), and with supporting documents
reasonably satisfactory to Tenant.  If Tenant's proportionate share of the
actual annual operating costs for 1994 (and subsequent years) exceeds Tenant's
proportionate share of the annual operating costs paid by Tenant for 1994 (and
subsequent years), Tenant shall pay the difference to Landlord in one lump sum,
along with the next payment of Base Rent due and payable.  If Tenant's
proportionate share of the actual annual operating costs for 1994 (and
subsequent years) is less than Tenant's proportionate share of the annual
operating costs paid by Tenant for 1994 (and subsequent years), Landlord shall
credit the difference to Tenant as an offset against the next payment of Base
Rent due and payable.  Until actual annual operating costs for any given year
are determined, Tenant shall pay annual operating costs for and during that
given year based on the most recently computed annual operating costs figure.
Notwithstanding the foregoing, Tenant shall not be liable for any increases in
1994 operating costs attributable to that pro-rata period of time during 1994
which constitutes the second year of this lease (e.g. if the commencement date
is September 1, 1992, then the second year expires on August 31, 1994, and
Tenant will be responsible for increases in operating costs only for the
pro-rata period after August 31, 1994).  Further notwithstanding the foregoing,
operating costs increases charged to Tenant after the first two years of this
lease shall not exceed 5% per year, regardless of the actual increases.

         (e)     DISPUTES:  Any statement of actual annual operating costs
furnished to Tenant by Landlord under 4(d) shall constitute a final
determination of same, unless Tenant, within 30 days after the statement is
furnished, gives notice to Landlord that Tenant disputes the correctness of the
statement, specifying the basis for such assertion.  Pending resolution of such
dispute, Tenant shall pay the annual operating costs to Landlord, in accordance
with the statement.  Landlord agrees, upon written request and during normal
business hours, to make available for Tenant's reasonable inspection (including
inspection by Tenant's accountants), at Landlord's office, Landlord's books and
records relevant to any items in dispute.  If errors are determined to exist in
accordance with generally accepted accounting principles, revisions to the
statement shall be made accordingly.

         (f)     LEASE TAX:  Tenant shall pay to Landlord the tax imposed by
F.S. 212.031 (or any successor statute) upon the rent, along with and included
in every monthly payment of rent.  Other than any income or inheritance tax,
Tenant shall pay any additional local, state or federal tax imposed upon
Tenant's use and occupancy of the Premises, and upon the rent payable
hereunder.

         (g)     SECURITY DEPOSIT: Simultaneously upon the execution hereof,
and in addition to all sums mentioned elsewhere in this lease, Tenant shall
deliver and pay to Landlord a security deposit in the amount of $16,681.35, as
security for Tenant's faithful performance of each and every provision of this
lease.  This security deposit is not advance rent, and will not be applied
towards rent, except at Landlord's sole discretion and option.  Nor is this a
provision for or limitation upon damages, in the event Tenant breaches this
lease by vacating prior to the end of the term, or otherwise breaches this
lease.  These funds shall not be interest-bearing to Tenant, and may be
commingled by Landlord.  Upon the expiration of the term, and in the event
Tenant has faithfully and timely complied with and discharged all of its
covenants and obligations, these funds shall be returned to Tenant within ten
days of the last day of the term.



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<PAGE>   4

         (h)     SUMMARY OF MONTHLY PAYMENTS:

<TABLE>
                 <S>              <C>
                 $ 9,399.81       representing Base Rent of $7.10 per square foot during years 1-5

                 $ 7,281.54       representing Tenant's proportionate share of operating costs during years 1-2

                 $ 1,000.88       representing the tax on the foregoing

                 ----------
                 $17,682.23
</TABLE>

         (i)     SUMMARY OF PAYMENTS DUE UPON EXECUTION OF LEASE:

<TABLE>
                 <S>              <C>
                 $16,681.35       security deposit

                 $ 9,399.81       base rent for first month of lease (targeted to be September, 1992)

                 $ 7,281.54       operating expenses for first month of lease (targeted to be September, 1992)

                 $ 1,000.88       tax on first month's rent and operating expenses

                 ----------
                 $34,336.58
</TABLE>

         5.      COVENANT TO PAY RENT AND ADDITIONAL RENT; LATE CHARGE: Tenant
shall, without demand, setoff or deduction, pay the Base Rent, operating costs,
and all other sums due under this lease, at the times and in the manner
required.  If any payment is overdue for 15 days, a late charge of 5% shall be
charged by Landlord, together with interest from the date when the payment was
due, at 15%.  Nothing herein shall be construed as waiving any rights of
Landlord resulting from any default by Tenant, by reason of Landlord's
assessing or accepting any such late payment, late charge, or interest, and the
late charge and interest assessed herein are separate from and in addition to
any other remedies of Landlord after default by Tenant.

         6.      USE: The Premises are to be used by Tenant for general office 
purposes only.

         7.      ASSIGNMENT AND SUBLETTING: In entering into this lease,
Landlord has relied upon the integrity, reputation and creditworthiness of
Tenant.  Accordingly, Tenant shall not assign this lease or sublet the Premises
or any part thereof, or permit any other person or entity to occupy the
Premises, without first obtaining Landlord's written consent, which consent
will not be unreasonably withheld.  However, neither Landlord's consent, nor
any assignment or subletting, shall release Tenant from liability for the
performance of all the terms, covenants and conditions of this lease.
Furthermore, no assignment or sublease will be valid unless the
assignee/subtenant executes and delivers to Landlord an assumption of liability
agreement, in form satisfactory to Landlord.

         8.      IMPROVEMENT OF THE PREMISES:

                 (a)      LANDLORD'S PRELIMINARY SPACE PLAN: Landlord has
delivered to Tenant a floor plan (Exhibit "A").  Tenant shall designate in
writing a single individual to meet with Landlord at the Premises as Tenant's
representative in connection with this Article 8, and said representative shall
have the authority to legally bind Tenant.

                 (b)      TENANT'S CONSTRUCTION PLANS: Tenant shall have
prepared, using the architect or engineer designated by Landlord, at Landlord's
expense, and not later than July 8, 1992, construction plans prepared by such
architect or engineer, which plans shall be deemed a part of this lease.
Tenant's Construction Plans shall designate, among other things, the locations
of and specifications for all plumbing, electrical and mechanical equipment to
be installed in the Premises, all partitions, doors,



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<PAGE>   5

lighting fixtures, electric receptacles and switches, telephone outlets and
special air conditioning, floor coverings and other improvements to be
installed by Landlord.

                 (c)      CERTAIN CHANGES: Tenant shall pay to Landlord on
demand the reasonable amount of Landlord's architectural and engineering fees
(i) resulting from any changes made in Tenant's floor plan or Tenant's
construction plans (hereinafter collectively referred to as Tenant's
Construction Plans), at Tenant's request; or (ii) necessitated as a result of
changes in Tenant's Construction Plans made after Landlord shall have released
them to its contractor.

                 (d)      RESTRICTED CHANGES: Should Tenant desire to make
changes to any approved plans which are so substantial as to cause postponement
of the commencement date, without prejudice to the provisions of Article 3(b)
hereof, Landlord shall have the right to refuse to permit the making of such
changes unless and until Tenant shall have committed in writing, in a manner
reasonably satisfactory to Landlord, to pay Landlord on the date rent would
have commenced in the absence of such delay, a sum of money equivalent to the
rent for the Premises for the period during which Tenant would have been
obligated to pay rent to Landlord had the commencement date not been so
delayed.  Furthermore, no change requested by Tenant, whether or not
substantial, shall be effective unless and until (in addition to any other
conditions as herein specified) Landlord and Tenant agree in writing as to the
additional cost to Tenant on account thereof.

                 (e)      COMPLETION BY LANDLORD; CHANGES:  Landlord shall, in
a good and workmanlike manner, cause the Premises to be improved and completed
in accordance with the Floor Plan (Exhibit "A") and Tenant Work Workletter
(Exhibit "C").  Landlord reserves the right, however: (i) to make substitutions
of material of equivalent grade and quality when and if any specified material
is not readily and reasonably available, and (ii) to make changes necessitated
by conditions met in the course of construction, provided that Tenant's
approval of any substantial change shall first be obtained (which approval
shall not be unreasonably withheld or delayed, so long as there shall be
general conformity with the Floor Plan).

                 (f)      TENANT WORK (EXHIBIT "C")/ADDITIONAL WORK: In the
completion and preparation of the Premises in accordance with the Floor Plan
(Exhibit "A"), Landlord agrees to perform at its own expense those items of
work set forth on Exhibit "C" (Tenant Work Workletter).  Any work to be
performed by Landlord in addition to or in substitution of Exhibit "C" is
referred to as Additional Work.  All Additional Work shall be
furnished/performed by Landlord, at Tenant's sole expense, based on "Landlord's
Cost." Landlord's Cost means Landlord's out-of-pocket or purchase price for
materials, labor and services including any reasonable contractor's fee for the
contractor's overhead and profit, and charges for cutting, patching, cleaning
up and removal of waste and debris, plus architects' and engineers' fees, plus
the product obtained by multiplying all of the foregoing (as reduced by
appropriate credits) by fifteen percent (15%) for Landlord's expenses and
profit in handling any substitution; provided, however, that in no event may
Tenant be required to pay more than the prevailing cost in Broward County,
Florida, for similar work.

                 (g)      PAYMENT FOR ADDITIONAL WORK:  Tenant shall pay
Landlord for all Additional Work from time to time during the progress of the
work, within fifteen (15) days after Landlord gives Tenant an invoice therefor.
Upon presentation of the final invoice, the total Landlord's cost shall be
subject to verification by Tenant, and Tenant shall have reasonable access to
Landlord's cost records.  In the event Tenant fails to reimburse Landlord as
provided herein, interest shall commence to accrue upon Landlord's cost, as of
the due date, at the maximum rate permitted by law, and the total payment
required hereby shall be deemed additional rent.

                 (h)      ACCESS, ACCEPTANCE OF WORK:  Landlord shall afford
Tenant access to the Premises, at reasonable times prior to the commencement
date, and at Tenant's sole risk, for the purpose of inspecting the performance
of "Tenant Work," and any Additional Work, and Tenant shall advise Landlord
promptly of any objection to the performance of such work.  Landlord shall
promptly undertake the correction of any defective work.  On the commencement
date, all Tenant Work or Additional Work not objected to by Tenant shall be
deemed satisfactory.  The foregoing presumption shall not apply,



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however: (i) to Tenant Work or Additional Work not actually completed by
Landlord, which Landlord agrees shall be completed within 30 days; or (ii) to
latent defects in such Tenant Work, or Additional Work, which could not
reasonably have been discovered, provided Tenant notifies Landlord thereof
within three months after occupancy.

         9.      ALTERATIONS: No alterations or additions shall be made to the
Premises without Tenant first submitting a description thereof to Landlord, and
obtain Landlord's written approval, which will not be unreasonably withheld.
All alterations/additions made by Tenant, and all fixtures permanently attached
to the Premises shall become the property of Landlord, and remain at the
Premises or, at Landlord's option, after written notice to Tenant, any or all
of the foregoing shall be removed at Tenant's expense at the termination of
this lease, and Tenant shall repair all damage to the Premises caused by said
installation/removal.  At the time of Landlord's approval, Landlord shall
notify Tenant if the improvements must be removed at the termination of this
lease.  Tenant shall not place any sign or advertising matter on the Premises
without the prior written consent of Landlord (except for the permitted
signage, Article 36 infra).  Tenant shall not place equipment that weighs more
than the safe carrying capacity of the building.

         10.     RULES AND REGULATIONS: The rules and regulations attached as
Exhibit "D," and such reasonable additions/modifications as may be made by
Landlord upon written notice to Tenant, are a part of this lease, and Tenant
covenants to faithfully observe said rules and regulations.

         11.     FIRE OR OTHER CASUALTY: If the building is so damaged by fire
or other casualty that the Premises are rendered unfit for occupancy (whether
or not the Premises are damaged), then, at either party's option, the term of
this lease, upon written notice from such party given within 30 days after the
occurrence of such damage, shall terminate as of the date of the fire or other
casualty.  In such case, Tenant shall pay the rent apportioned to the time of
such termination, and Landlord may enter upon and repossess the premises
without further notice.  If neither party elects to terminate the term of this
lease, Landlord will repair the building, and Landlord may enter and possess
the Premises for that purpose.  While Tenant is deprived of the Premises, rent
shall be suspended in proportion to the number of square feet of the Premises
rendered untenantable.  If the Premises or the building shall be damaged so
that such damage does not render the Premises unfit for occupancy, Landlord
will repair whatever portion of the Premises or of the building that may have
been damaged, and Tenant will continue in possession, and rent will be
apportioned or suspended to the extent that the Premises are partially
untenantable as a result of the damage.  In the event Landlord elects to repair
or rebuild the Premises pursuant to this paragraph, Tenant agrees to furnish
Landlord with all insurance proceeds which Tenant recovers for damage to the
Premises, excluding improvements paid for by Tenant.  The reconstruction of the
Premises beyond Exhibit "C" shall be Tenant's sole responsibility, at Tenant's
option.  Despite any other provisions of this Article 11, if any damage is
caused by or results from the gross negligence of Tenant, those claiming under
Tenant, or their employees or invitees, rent shall not be suspended or
apportioned, and Tenant shall pay, as additional rent upon demand, the cost of
any repairs, made or to be made, as a result of such damage.  Any lack of
telephone service (except any lack of telephone service caused by or the fault
of Southern Bell), any lack of air conditioning, and any lack of electricity
(except any lack of electricity caused by or the fault of Florida Power &
Light) that continues for more than five working days shall render the Premises
unfit for occupancy, and shall entitle Tenant to the abatement of rent in
16(c).

         12.     ACCESS TO PREMISES: Landlord shall have the right to enter and
pass through the Premises, to make any repairs, or due to any emergency
affecting the Premises or any other part of the building or property.  Tenant
shall provide Landlord with a key to the Premises, and shall not change its
locks or keys without Landlord's prior written consent, and without delivering
to Landlord a key for said locks.  At any reasonable time, Landlord may, upon
reasonable notice to Tenant, enter the Premises with a prospective Tenant,
purchaser, mortgagee, investor, or similar party, and exhibit the Premises to
said party.  All of the foregoing access (except emergency access) shall be
during normal business hours only.  Furthermore, no access whatsoever shall be
permitted to the computer areas (including cleaning personnel).



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<PAGE>   7

         13.     INSURANCE:

                 (a)      Tenant will not commit any act or permit any act to
be committed, as a result of which either any policy of insurance on the
property shall become void or suspended, or the insurance risk on the building
shall be rendered more hazardous.

                 (b)      Tenant shall maintain, at its expense, and at all
times during the term of this lease, a comprehensive general public liability
policy insuring against loss or liability in connection with bodily injury,
death, and property damage in or upon the Premises or the remainder of the
property, and arising out of the use of same by Tenant or its agents,
employees, invitees, visitors, and guests, with limits or not less than One
Million Dollars ($1,000,000.00). It is agreed and understood that the policy
required hereby shall apply as the primary source of recovery, without regard
to legal liability for loss.  Such policy shall name Landlord as an additional
insured.  A duplicate of said policy shall be promptly delivered to Landlord,
and not less than 20 days prior to the expiration of said policy, Tenant shall
deliver to Landlord a paid receipt for the renewal premium.  If Tenant fails to
perform its obligations hereunder, Landlord may (but shall not be obligated to)
perform same, and the cost shall be additional rent immediately due and
payable.

                 (c)      Landlord shall maintain fire/hazard coverage upon the
building.  The cost of the premium for such insurance shall be deemed, for
purposes of Article 4 of this lease, to be a cost of operating and maintaining
the property.

         14.     CONDITION OF PREMISES: Upon the termination of this lease,
Tenant shall leave the Premises, and during the term will maintain same, in the
same order and condition as existed at the commencement date, ordinary wear and
tear, damage by fire or other casualty (which fire or other casualty has not
occurred through the negligence of Tenant, or those claiming under or through
Tenant), and repairs to be performed by Landlord under Article 16, alone
excepted.  Tenant will use every reasonable precaution against fire and will
give Landlord prompt notice of any damage to or accident upon the Premises.

         15.     COMPLIANCE WITH LAWS:  Tenant agrees to comply promptly with 
all laws and requirements of any federal, state, county, or municipal 
authorities, or of the Board of Fire Underwriters, or of any insurance company, 
with respect to the Premises.

         16.     SERVICES:

                 (a)      Landlord agrees that it shall, at its expense, unless
otherwise stated:

                          (i)     HVAC: Furnish heat, ventilation and air
conditioning to the Premises, Monday through Friday from 7:00 A.M. to 7:00
P.M., and Saturdays from 7:00 A.M. to 1:00 P.M., excepting New Year's Day,
Memorial Day, Fourth of July, Labor Day, Thanksgiving Day and Christmas Day.
Heat, ventilation and air conditioning required by Tenant at other times shall
be supplied upon 24 hours' notice, and shall be paid for by Tenant at $10.00
per hour.  Tenant agrees to cooperate fully with Landlord and to abide by all
regulations reasonably prescribed for the proper functioning and protection of
the heating, ventilating and air conditioning system.  The foregoing heating,
ventilating and air conditioning services shall be subject to any statute,
ordinance, rule or regulation for energy conservation which may be promulgated
by any governmental agency.

                          (ii)    Elevators: Provide passenger elevator 
service at all times.

                          (iii)   Access: Furnish access to the Premises at all
times, subject to compliance with reasonable security measures.

                          (iv)    Janitorial: Provide janitorial service in
accordance with Exhibit "F"; any additional janitorial service desired by Tenant
shall be contracted for by Tenant directly with Landlord's janitorial agent at
Tenant's expense.  No trash removal services will be provided for a quantity
not



                                    7 of 12
<PAGE>   8

customary for normal office use.  Tenant recognizes that Landlord has control
over the actions of janitorial persons; accordingly, Landlord shall be liable 
for any loss, theft or damage to Tenant's property by reason of any janitors' 
acts.

                          (v)     Structural Repairs: Make all required
structural repairs; all required repairs to mechanical, HVAC, electrical and
plumbing systems (excluding repairs to any non-standard fixtures or other
improvements installed at the request of Tenant, requiring maintenance of a
type not customarily provided by Landlord to office tenants of the building),
and all repairs to exterior windows and glass.  In the event that any repair is
required because of the gross negligence or abuse of Tenant or its agents,
employees, or invitees, Landlord may make such repair and add the cost thereof
to the next installment of rent, unless Landlord shall have actually recovered
such cost through insurance proceeds.  If Tenant fails to reimburse Landlord
with the next rent installment, interest shall accrue on said amount at the
maximum rate permitted by law, and said amount shall be deemed additional rent.

                          (vi)    Water: Provide hot and cold water, for 
drinking and sanitary purposes, at each floor.

                          (vii)   Public Areas: Maintain the public areas in 
clean and good working order.

                          (viii)  Electricity: Furnish to Tenant electric
energy as required, but not exceeding the specifications in Exhibit "C".
Landlord shall not be liable for failure or defects in the supply of
electricity furnished to the Premises by reason of any requirement, act or
omission of Florida Power & Light, or for any other reason not attributable to
Landlord.

                 (b)      Special Equipment: Tenant shall not install any
equipment or use the Premises in a manner which would necessitate any changes,
replacements or additions to any of the heating, ventilating, air conditioning,
electric, sanitary, elevator or other systems serving the Premises or building;
or to any of the services required of Landlord.  The foregoing shall not apply
to additional air conditioning required for Tenant's computers.  Any machine or
equipment causing noise or vibration reasonably objectionable shall, at
Tenant's expense, promptly be placed and maintained by Tenant in settings of
cork, rubber or spring-type vibration eliminators, or subjected to other
measures sufficient to reduce such noise or vibration.

                 (c)      Interruption of Service: If the operation of the
elevators, heating, ventilation, air conditioning or any other service is
suspended due to war, accident, inability to obtain repairs, strikes, inability
to obtain supplies, or other causes beyond Landlord's control, same shall not
be a breach of this lease by Landlord.  However, in the event elevator or air
conditioning service is suspended for more than 5 working days, Tenant shall
receive an abatement of rent for any time beyond the 5th day that the elevators
or air conditioning service is suspended.

         17.     NOTICE OF BREAKAGE, FIRE, THEFT: Tenant shall give Landlord
written notice, within 24 hours, of any (a) accident or breakage or defects in
window glass, wires, plumbing, heating, ventilating, air conditioning, or
elevators; (b) fire or other casualty, or (c) theft.

         18.     RELEASE OF LANDLORD: To induce Landlord to enter into this
lease, and inasmuch as Tenant agrees to maintain and look to its own insurance
coverage in the event of any injury or property damage, Tenant hereby agrees
that except for Landlord's willful misconduct, Landlord shall not be held
responsible for, and is hereby expressly relieved from all liability for
injury, loss, or damage to any person or property of Tenant or of any other
person.  Tenant recognizes that Landlord has no control whatsoever over the
acts of third persons, including criminal acts.  No representations have been
made as to the safety or security of the building.  Tenant further agrees to
indemnify, defend, and hold Landlord harmless from and against all claims by
any employee or invitee of Tenant, made on account of such injury, loss or
damage, including but not limited to the reasonable attorney's fees and
expenses of litigation incurred in connection with defending any such claims.

         19.     intentionally omitted.


                                    8 of 12
<PAGE>   9

         20.     REMEDIES OF LANDLORD:

                 If Tenant (i) does not pay in full within 15 days after
receipt of written notice of default, as is set forth in subparagraph (D)
below, any installment of rent (whether Base Rent or Additional Rent), or any
other charge or monetary obligation; (ii) violates, fails to perform, or
otherwise breaks any material term, provision or condition of this lease, or
any other obligation imposed upon Tenant; or (iii) abandons the Premises:

                          (A)     Then, in any such event, the entire amount of
rent and charges for the balance of the term shall be immediately due and
payable and in arrears, and Tenant's right to occupy the Premises shall
terminate, without any right on the part of Tenant to reinstate by payment of
any sum, or by performance of any obligation.

                          (B)     In the event of Tenant's bankruptcy, Tenant
hereby stipulates that Landlord shall have immediate relief from the automatic
stay, or alternatively, Tenant shall provide Landlord with adequate assurance
of Tenant's future performance of all of the terms, conditions and covenants of
this lease, including but not limited to the assumption of the lease, and the
immediate curing of any back-due rent and other payments.

                          (C)     Upon recovering the Premises, Landlord may
lease all or part thereof, and Tenant shall be liable for any deficiency, plus
the costs and expenses of reletting and of making reasonably necessary repairs
and alterations to the Premises.

                          (D)     No default in any payment by Tenant shall be
deemed to have occurred unless and until Landlord provides Tenant with 15 days
written notice specifying the default.  Any notice by Landlord to Tenant under
this subparagraph (D) shall be deemed to have been received by Tenant two days
after being send via certified mail, regardless of whether the receipt is
signed.  Provided, however, that Tenant shall not be entitled to such notice
and grace period more than twice in any 12 month period, and further provided
that this subparagraph (D) is in addition to the late charge imposed by Article
5.

                          (E)     Tenant agrees to collaterally assign to
Landlord, as security for the performance of Tenant's obligations hereunder,
all of Tenant's rights, title, and interest in and to all furniture, fixtures,
and equipment brought on the premises.  This shall be in the form of a UCC-1
and chattel mortgage.  All recording expenses and the like shall be borne by
Landlord.  Tenant shall provide Landlord with a sufficient description of said
furniture, fixtures, and equipment, including serial numbers, and shall update
the description if additional or different furniture, fixtures, and equipment
are brought on the premises.  To the extent required by Tenant's lenders,
Landlord will subordinate its lien under this paragraph 20(E).

         21.     REMEDIES CUMULATIVE; ATTORNEY'S FEES: All remedies available
to Landlord under this lease are cumulative and concurrent.  No termination of
Tenant's right to occupy the Premises, or taking possession of the Premises by
Landlord, or the reletting of same, shall deprive Landlord of any remedies or
causes of action against Tenant for rent, for charges or for damages, nor shall
the bringing of any action, nor the resort to any other remedy or right, be
construed as a waiver or release of any other rights, remedies, or causes of
action.  The failure of either party to insist upon strict and/or prompt
performance of the terms of this lease, and the acceptance of such performance
thereafter, shall not be construed as a waiver of such party's right to
thereafter enforce same strictly.  In the event of any litigation, the losing
party shall pay the prevailing party's reasonable attorney's fees, court costs,
and reasonable expenses of litigation.  Tenant's tender and Landlord's physical
acceptance (and endorsement and deposit, as the case may be) of partial rent
and other charges shall in no way eliminate Tenant's obligation to pay all rent
and other charges due, nor shall same constitute a waiver by Landlord or
preclude Landlord from an action for eviction, damages, or both, based, in
whole or in part, on nonpayment of late charges, nor shall same in any way
constitute an accord and satisfaction between the parties, or a novation of
this lease.  No legend or memo on the front or back of any check, and no
letter, note or memo accompanying any check, and Landlord's physical acceptance
(and endorsement and



                                    9 of 12
<PAGE>   10

deposit, as the case may be), shall in any constitute an accord and
satisfaction between the parties, a waiver by Landlord, or a novation of this
lease, when the amount tendered by Tenant is less than the amount due under
this Lease.

         22.     LEASE SUBORDINATED:  This lease is subordinate at all times to
any mortgage or any encumbrance on Landlord's interest in the Premises.  At
Tenant's request, Landlord will request a Non-Disturbance Agreement from
American Bank of Hollywood, in favor of Tenant.

         23.     CONDEMNATION: If the whole or a substantial part of the
building is taken or condemned for public use, Tenant shall have no claim
against Landlord, and shall have no claim to any portion of the amount that may
be awarded to Landlord as damages or paid as a result of such condemnation,
including any right of Tenant to damages for loss of its leasehold.  All rights
of Tenant to damages therefor are hereby assigned by Tenant to Landlord.  The
foregoing shall not, however, deprive Tenant of any separate award for moving
expenses, business dislocation damages, or for any other award which would not
reduce the award payable to Landlord.  Upon the date the right to possession
vests in the condemning authority, this lease shall cease and terminate with
rent adjusted to such date, and Tenant shall have no claim against Landlord for
the value of any unexpired term of this lease.

         24.     NOTICES: All notices required to be given by Landlord to
Tenant shall be sent via certified mail, return receipt requested, to Tenant at
the Premises.  All notices required to be given by Tenant to Landlord shall be
sent via certified mail, return receipt requested, to Landlord at 6100
Hollywood Boulevard, Suite 206, Hollywood, Florida 33024, with a copy to
Michael P. Gable, 4000 Hollywood Boulevard, Suite 485 South, Hollywood, Florida
33021-6744, or such other persons as Landlord designates in writing.

         25.     DEFINITION OF LANDLORD: Landlord is deemed as HORIZON
ASSOCIATES JOINT VENTURE, and its successors, assignees, vendees, and the heirs
and personal representatives of any individual successors, assignees or
vendees.  No officer, director, manager, or employee/agent of Landlord, or of
any partner of Landlord, shall be subject to any individual liability
hereunder.

         26.     DEFINITION OF TENANT: Tenant includes NATIONAL COMPUTER
DISTRIBUTORS and its successors, assignees, and vendees, subject to Article 7.
No officer, director, manager, or employee/agent of Tenant shall be subject to
any individual liability hereunder, except for fraud, or conveyances to hinder
or delay Landlord as a creditor.

         27.     ESTOPPEL: At Landlord's request, Tenant shall sign an estoppel
letter setting forth the amounts of rent paid/due, commencement and termination
dates, and such other matters as are customarily contained in estoppel letters.

         28.     SEVERABILITY: No adjudication by any court or governmental
agency that any provision or portion of any provision of this lease is invalid
or unenforceable shall affect the validity or enforceability of the remainder
of that provision, or of any other provision of this lease, which shall remain
valid and enforceable to the fullest extent allowed by law.

         29.      NAME OF BUILDING; CAPTIONS; INTERPRETATIONS/EXHIBITS: The
building may be designated by any name Landlord chooses, upon 60 days notice.
Captions in this lease are for convenience only, and are not to be used in
interpreting this lease.  There shall be no interpretation of this lease in
favor of either party by virtue of its preparation by Landlord.  Every exhibit
attached to this lease is hereby made a part of this lease.

         30.     BROKERS: Tenant represents that it has not dealt with any real
estate brokers in the negotiation or execution of this lease, other than ANF
Group, Inc., and Property Trust Realty, Inc.  Tenant shall indemnify Landlord
against the claims of any other brokers claiming to have dealt with Tenant.
Landlord shall be responsible for the payment of any commission due ANF Group,
Inc., and Property Trust Realty, Inc., and shall indemnify Tenant against the
claims of any other brokers claiming to have dealt with Landlord.



                                    10 of 12
<PAGE>   11

         31.     WAIVER OF JURY TRIAL: The parties waive trial by jury in any
litigation, including counterclaims, arising out of or in any way connected
with this lease, their relationship as Landlord and Tenant, and Tenant's use
and occupancy of the Premises.

         32.     ENTIRE AGREEMENT:  This lease and the attached exhibits
constitute the entire agreement between Landlord and Tenant.  There are no
representations or understandings other than those set forth herein.  No
subsequent understanding or modification to this lease shall be binding upon
Landlord or Tenant unless reduced to writing and signed by that party.

         33.     GOVERNING LAW:  This lease shall be governed by Florida law.
Venue for any action shall be Broward County, Florida.

         34.     TIME:  Time is of the essence with respect to the performance
of all the provisions hereof.

         35.     MISCELLANEOUS PROVISIONS: The following provisions supersede
the preceding provisions, to the extent inconsistent herewith.

                (a)   SIGNAGE: Tenant will be permitted to install its
                      corporate name (NCD) on the uppermost face of the east
                      and west sides of the building at Tenant's expense.  No
                      other signage will be permitted on the building.  The
                      foregoing is subject to approval by the City of
                      Hollywood, and compliance with applicable City Code
                      provisions.

                (b)   ELEVATOR SERVICE: On any floor that Tenant occupies in
                      its entirety, all elevators shall be programmed by
                      Landlord to lock off for Tenant accessibility only.

                (c)   EMERGENCY POWER: The building generator shall be
                      engineered to provide Tenant with back-up power in the
                      event of a power failure, to certain areas depicted in the
                      electrical plans. (Specifically computer room and sales
                      area).

                (d)   PARKING: Tenant shall be entitled to free on-site
                      parking throughout the term of the lease and any
                      extensions.  One parking space for every 1,000 square
                      feet of office space leased shall be reserved undercover,
                      to be installed prior to the Certificate of Occupancy,
                      in a mutually acceptable location (as per Exhibit "G").

                (e)   EXPANSION OPTION: Within one (1) year of the lease
                      commencement date, Tenant shall have the right to expand
                      into any or all of the 6th floor of the building.  The
                      rental rate for any and all expansion space shall be
                      $13.00 per square foot, including operating costs.  If,
                      after one year, no expansion take place, Tenant shall
                      have one (1) additional year within which to expand into
                      50% of the 6th floor.  If within the first year, Tenant
                      expands into at least 50% of the 6th floor, then Tenant
                      shall have the next ensuing year within which to expand
                      into the balance of the 6th floor.  Notwithstanding
                      anything to the contrary, the term, with respect to any
                      and all expansion space, shall expire when the term for
                      the original space expires, in accordance with 3(a). 
                      Tenant shall have the aforesaid time periods within which
                      to exercise its options (not within which to occupy the
                      expansion space).  With respect to the first year
                      expansion option, space up to 7,500 feet shall be
                      provided by Landlord within 90 days.  If Tenant opts to
                      take more than 7,500 feet, Landlord shall have 120 days
                      to provide occupancy.  Attached hereto is Exhibit
                      "C-1" is a workletter describing the Tenant Improvements
                      for the 6th floor.


                                    11 of 12
<PAGE>   12


         36.     QUIET ENJOYMENT: Upon compliance with all of its obligations
hereunder, Tenant shall have the quiet enjoyment of the premises.

         37.     EXCLUSIVITY: No other wholesale computer distributor shall be
permitted to occupy space in the building.

         38.     MAINTENANCE/CONDITION: Landlord will maintain the building as
a first class office building, in the same condition as existed at the
commencement of the lease, reasonable wear and tear excepted.

         IN WITNESS WHEREOF, the parties have executed this lease.



                                        LANDLORD:
                                        HORIZON ASSOCIATES JOINT VENTURE
                                        By: HORIZON-ANF, INC., General Partner


/s/                                     By  /s/ Nelson Fernandez      7-8-92
--------------------------------           ------------------------- ---------
First Witness as to Landlord                  Nelson Fernandez,       Date
                                              Secretary/Treasurer    

/s/ Kimberly
--------------------------------
Second Witness as to Landlord


                                        TENANT:
                                        ROSS WHITE ENTERPRISES, INC.
                                        d/b/a NATIONAL COMPUTER DISTRIBUTORS,


/s/                                     By:  /s/ Gregory A. White     7-8-92
--------------------------------           ----------------------------------
First Witness as to Tenant                  Gregory A. White,         Date
                                            President

/s/ Kimberly
--------------------------------
Second Witness as to Tenant



                                   12 of 12
<PAGE>   13

                         EXHIBIT D - RULES/REGULATIONS


         1.      The walkways, roadways, driveways, entrances, lobbies,
passages, elevators and stairways shall not be obstructed by Tenant or used by
Tenant for any purpose other than egress from and to the building and Tenant's
offices.  The parking areas shall be used only for the parking of automobiles
of Tenant, its agents, employees and invitees while actually present on the
Premises.  Landlord shall in all cases retain right to control or prevent
access to all of the aforesaid area of all persons whose presence, in the
reasonable judgment of Landlord, shall be prejudicial to the safety, peace,
character, or reputation of the Building, the property located therein or of
any of the tenants.  Landlord shall in no case be liable for damages for the
admission or execution of any person from the Building.

         2.      The toilet rooms, water closets, sinks, faucets, plumbing or
other service apparatus of any kind shall not be used by Tenant for any purpose
other than those for which they were installed, and no sweepings, rubbish,
rags, ashes, chemicals or other refuse or injurious substances shall be placed
therein or used in connection therewith by Tenant or left by Tenant in the
lobbies, passages, elevators or stairways.  Nothing shall be thrown by Tenant
or Tenant's employees nor be allowed by them to drop out of the windows or
doors, or down the passages of the Building.

         3.      Nothing shall be placed by Tenant on the outside of the
Building or on its window sills or projections.  Skylights, windows, doors and
transoms shall not be covered or obstructed by Tenant, and no window shades,
blinds, curtains, screens, storm windows, awnings or other materials shall be
installed or placed on any of the windows or in any of the window spaces,
except as approved in writing by Landlord.

         4.      No signs, lettering insignia, advertisement or notice shall be
inscribed, painted, installed or placed on any window space or any other part
of the outside or inside of the Building, unless first approved in writing by
Landlord, at Tenant's expense.  In all instances, such names shall be of design
and form first approved by Landlord.

         5.      Tenant shall not place additional locks upon any doors.  The
janitor and the manager of the Building may at all times keep a pass key, and
he and other agents of the Landlord shall at all reasonable times be allowed
admittance to the leased Premises for purposes permitted in Tenant's lease
(provided Tenant's quiet enjoyment is not unnecessarily or unduly disturbed).
Upon surrendering possession of the Premises at the termination of this Lease,
Tenant shall deliver to Landlord all keys for the Premises.

         6.      The delivery of towels, ice, water, beverages, newspapers, and
other supplies will be permitted only under the direction, control and
supervision of Landlord.  No bicycles or similar vehicles will be allowed in
the Building.

         7.      Tenant shall not do or commit, or suffer to be done or
committed, any act or thing whereby, or in consequence whereof, the rights of
other tenants will be obstructed or interfered with, or other tenants will in
any other way be injured or annoyed, or whereby the Building will be damaged.
Tenant shall not suffer or permit the Premises or any part thereof to be used
in any manner or anything be done therein or suffer or permit anything to be
brought into or kept in the Premises which, in the judgment of Landlord, shall
in any way impair or tend to impair the character, reputation or appearance of
the Building as a first-class office building.  Tenant shall not use or keep or
permit to be used or kept in the Building any matter having an offensive odor,
nor any ether, naphtha, phosphorous, benzol, kerosene, gasoline, benzine,
camphene, fuel or other explosive or highly flammable material.  Tenant shall
neither bring, keep or use in the Building any chemical agent except as the
same may be components or commercial products normally used or consumed by
occupants of office buildings.  No birds, fish or other animals shall be
brought into or kept or about the Premises.
<PAGE>   14

         8.      In order that the Premises may be kept in a good state of
preservation and cleanliness, Tenant shall during the continuance of its
possession permit Landlord's employees and contractors and no one else to clean
the Premises.  Landlord shall provide Tenant with a certificate of Landlord's
janitorial service's insurance.  Tenant shall see each day that the windows are
closed, lights are turned off, and the doors securely locked before leaving the
Premises.

         9.      If Tenant desires to introduce signaling telegraphic,
telephonic, protective alarm or other wires, apparatus or devices, Landlord
shall direct where and how the same are to be placed, and except as so
directed, no installation, boring or cutting shall be permitted.  Landlord
shall have the right to prevent and to cut off the transmission of excessive or
dangerous current of electricity or annoyances into or through the Building or
Premises and to require the changing of wiring connections or layout at
Tenant's expense, to the extent that Landlord may deem necessary, and further
to require compliance with such reasonable rules as Landlord may establish
relating thereto, and in the event of non-compliance with the requirements or
rules, Landlord shall have the right immediately to cut wiring or to do what it
considers necessary to remove the danger, annoyance or electrical interference
with apparatus in any part of the Building.  All wires installed by Tenant must
be clearly tagged at the distributing boards and junction boxed and elsewhere
required by Landlord, with the number of the office to which said wires lead,
and the purpose for which the wires respectively are used, together with the
name of the concern, if any, operating same.

         10.     A directory on a bulletin board on the ground floor will be
provided by Landlord, on which the name of the Tenant may be placed.  The size
of the name so listed and the location of the directory shall be at Landlord's
reasonable discretion.

         11.     No furniture of Tenant will be received in the building, or
carried up or down in the elevators or stairways, except during such hours as
shall be designated by Landlord, and Landlord in all cases shall also have the
exclusive right to prescribe the method and manner in which the same shall be
brought in or taken out of the Building.  Landlord shall in all cases have the
right to exclude from the Building heavy furniture, safes and other articles
which may be hazardous or to require them to be located at designated places in
the Premises.  The cost of repairing any damage to the Building caused by
taking in or out furniture, safes or any articles or any damage caused while
the same shall be in the Premises, shall be paid by Tenant.

         12.     Without Landlord's written consent, nothing shall be fastened
to, nor shall holes be drilled or nails or screws driven into walls or
partitions; nor shall walls or partition be painted, papered or otherwise
covered or moved in any way or marked or broken; nor shall any connection be
made to electric wires for running fans or motors or other apparatus, devices
or equipment, nor shall machinery of any kind other than customary small
business machines (personal computer equipment, fax machine, microwave and copy
machine) be allowed in the Premises; nor shall Tenant use any other method of
heating, ventilating, air conditioning, or air cooling than that provided by
Landlord.  Telephones, switchboards and telephone wiring and equipment shall be
placed only where designated by Landlord.  No mechanics shall be allowed to
work in or about the Building other than those employed by Landlord without the
written consent of Landlord first having been obtained.  The foregoing
paragraph excludes pictures and similar decorations, and Tenant's refrigerator
and icemaker.

         13.     Landlord shall, in no case, be responsible for the admission
or exclusion of any person to or from the Building for access to the Premises.
In cases of invasion, hostile attack, insurrection, mob violence, riot, public
excitement or other commotion, explosion, fire or any casualty, Landlord
reserves the right to bar or limit access to the Building for the safety of
occupants or protection of property.

         14.     Landlord reserves the right to rescind, suspend or modify any
rules or regulations and to make such other reasonable rules or regulations as,
in Landlord's reasonable judgment, may from time to time be needful for the
safety, care, maintenance, operation and cleanliness of the Building as a first
class building, or for the preservation of good order therein.  Notice of any
action by Landlord referred to in
<PAGE>   15

this paragraph, given to Tenant, shall have the same force and effect as if
originally made a part of the foregoing Lease.  New rules or regulations will
not, however, be unreasonably inconsistent with the proper use and enjoyment of
the Premises by Tenant under this Lease.

         15.     The use of rooms as sleeping quarters is prohibited at all
times.

         16.     Tenant shall keep the windows and doors of the Premises,
including those openings on corridors and all doors between rooms or spaces
entitled to receive heating, ventilating or air conditioning service and rooms
and spaces not entitled to receive such service, closed during the respective
times that the heating, ventilating or air conditioning system is operating, in
order to conserve the service and effectiveness of the heating, ventilating or
air conditioning system as the case may be.  Tenant shall comply with all
reasonable rules and regulations from time to time promulgated by Landlord to
conserve such services.

         17.     Landlord reserves the right to require that the Premises or
any portion thereof shall not be used by Tenant or others for an employment
agency, or for securing employees other than those to be employed on the
Premises, or for the payment of salaries or wages to employees or persons who
are not actually employed in the Building, nor for any other purposes except
that specified in the Lease.
<PAGE>   16

                                    ADDENDUM



         To that certain lease between HORIZON ASSOCIATES JOINT VENTURE as
Landlord, and ROSS WHITE ENTERPRISES, INC. d/b/a NATIONAL COMPUTER
DISTRIBUTORS, INC. as Tenant.

         WHEREAS, Article 35(a) of the lease permits Tenant to install certain
signage on the building at its expense, subject to approval by the City of
Hollywood, and compliance with applicable city code provisions, and

         WHEREAS, the parties wish to memorialize the fact that the signage
will conform to the attached exhibit, and that Tenant will indemnify and hold
Landlord harmless from any and all property damage and personal injury in any
manner connected with, related to, or arising from said signage, including but
not limited to installation, maintenance and removal thereof,

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, and intending to be legally
bound, the parties agree as follows:

         1.      The foregoing recitals are true, correct, and incorporated
herein.

         2.      Tenant hereby agrees to and shall fully indemnify and hold
Landlord harmless from and against any and all property damage whatsoever, and
personal injury whatsoever, in any manner connected with, related to, or
arising from said signage, including but not limited to the installation,
maintenance and removal thereof, regardless of the cause of any such damage or
injury, and regardless of any negligence on Landlord's part, it being
understood that Landlord is relying on Tenant for all matters pertaining to the
installation, maintenance and removal of the signage.

         3.      This agreement shall survive the expiration of the term of the
lease, if the signage is not removed prior thereto, and if Tenant has not
performed any of its obligations hereunder, this agreement shall survive until
all of its obligations are performed.

         4.      This indemnification and hold harmless includes the defense of
any litigation or demands, and the payment of any awards or judgments,
including principal interest, costs, and attorney's fees.


                                        LANDLORD:
                                        Horizon Associates Joint Venture
                                        By: Horizon-ANF, Inc., General Partner

                                        By:  /s/ Nelson Fernandez,     7-5-92 
                                            -----------------------------------
                                             Nelson Fernandez,           Date
                                             Secretary/Treasurer    

                                        TENANT:
                                        Ross White Enterprises, Inc. 
                                        d/b/a National Computer Distributors, 
                                        Inc.


                                        By: /s/ Thomas E. Ross          7-8-92 
                                            -----------------------------------
                                             Thomas F. Ross             Date
                                             Vice President
                                                  
<PAGE>   17

                               ADDENDUM TO LEASE

         WHEREAS, HORIZON ASSOCIATES JOINT VENTURE as Landlord, and ROSS WHITE
ENTERPRISES, INC. d/b/a NATIONAL COMPUTER DISTRIBUTORS, INC. as Tenant executed
the preceding Lease as of July 8, 1992, and

         WHEREAS, paragraph 35(e) provides for an expansion option with
respect to the sixth floor, and 

         WHEREAS, via this Addendum, Tenant wishes to exercise, and the
parties wish to formalize the terms and conditions of said option, and of the
parties' obligations regarding the expansion space,

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, and intending to be legally
bound, the parties agree as follows:

         1.      The foregoing recitals are true, correct and incorporated
herein.  All references herein to paragraphs are to the paragraphs as they
appear in the underlying lease.

         2.      Tenant hereby exercises its option to expand into the entire
sixth floor, being 15,418 rentable square feet.

         3.      The targeted occupancy/commencement date is January 1, 1994.

         4.      For the first sixth months of occupancy, Tenant shall pay base
rent and operating costs at the total rate of $6.50 per square foot per year,
plus tax on the foregoing.  This supersedes paragraph 35(e) to the extent
inconsistent therewith.  After the first six months, and for the remainder of
the duration of the original five year term of this lease, Tenant shall pay
base rent at the rate of $7.50 per square foot per year.  Tenant's
proportionate share of annual operating costs for this expanded space after the
first six months, and lease tax for this expanded space after the first six
months, shall be paid in accordance with paragraphs 4(d) and 4(f),
respectively, to-wit $5.50 per square foot per year until August 31, 1994.
Thereafter, Tenant's proportionate share of annual operating costs shall be
adjusted in accordance with 4(d)(iii).  Beyond the duration of the original
five year term of this lease, i.e. for and during any and all renewal option
periods, base rent shall be paid in accordance with the rates in 4(b), and
annual operating costs shall be paid and adjusted in accordance with the
formula in 4(d).

         5.      Landlord shall construct and install, at Tenant's expense but
at Landlord's cost, as



                                     1 of 2
<PAGE>   18

defined in paragraph 8(f), the special tenant work shown on the architectural
floor plan dated 10/21/93.  Tenant shall pay Landlord for these items upon
Landlord's substantial completion thereof.  However, the standard tenant
improvements shall be constructed at Landlord's expense.

         6.      Except to the extent, if any, modified above, all other terms,
conditions and provisions of the lease shall be binding on and applicable to
the expansion space, as if the expansion space were originally included in the
underlying lease.

         7.      So as to eliminate any confusion or misunderstanding, a
summary of payments for January, 1994 (assuming the expansion space is
completed as of January, 1994) is as follows:

<TABLE>
                 <S>              <C>
                 $ 9,399.81       base rent of $7.10 per square foot per year for Suite 700
                   7,281.54       Tenant's proportionate share of operating costs for Suite 700
                   1,000.88       tax on the foregoing
                   8,351.41       base rent and operating costs totaling $6.50 per square foot per year for
                                  the sixth floor for the first six months
                     501.08       tax on the foregoing

                 ----------
                 $26,534.72       Total due January 1, 1994
</TABLE>



/s/ Thomas F. Ross                        LANDLORD:
----------------------------------------  Horizon Associates Joint Venture 
Signature of first witness as to Landlord By: Horizon-ANF, Inc., General Partner
                                                                         

/s/ Thomas F. Ross                        By: /s/ Nelson Fernandez     10/25/96
----------------------------------------      ---------------------------------
Typewritten name of first witness                 Nelson Fernandez,    Date
as to Landlord                                    Secretary/Treasurer       

/s/ Audrey A. Hynes
----------------------------------------
Signature of second witness as to Landlord

/s/ Audrey A. Hynes
----------------------------------------
Typewritten name of second witness as
to Landlord



/s/ Thomas F. Ross                         TENANT:
----------------------------------------   Ross White Enterprises, Inc.
Signature of first witness as to Tenant    d/b/a National Computer
                                           Distributors, Inc.
                                          
                                          
 /s/ Thomas F. Ross                        By: /s/ Gregory A. White    10-25-93
----------------------------------------       -------------------------------- 
Typewritten name of first witness as to        Gregory A. White,       Date   
Tenant                                         President                      
                                                                       
                         

/s/ Audrey A. Hynes
----------------------------------------
Signature of second witness as to Tenant


/s/ Audrey A. Hynes
-----------------------------------------
Typewritten name of second witness as to Tenant



                                     2 of 2
<PAGE>   19


                       HORIZON ASSOCIATES JOINT VENTURE

                     6100 HOLLYWOOD BOULEVARD, SUITE 206

                           HOLLYWOOD, FLORIDA 33024



February 28, 1994

Mr. Gregory White
National Computer Distributors
6100 Hollywood Boulevard, Suite 700
Hollywood, Florida 33024

RE:  SUITE 500, EXPANSION SPACE ON FIFTH FLOOR, HORIZON ONE

Dear Greg:

Below, I have attempted to summarize our conversations regarding your expansion
into suite 500.  Please review the issues outlined below and if you agree with
them, please acknowledge so with your signature in the space provided.

1)       NCD shall lease suite 500, containing approximately 3,963 rentable
         s.f. for two concurrent periods; the first shall begin May 1, 1994 and
         end on October 31, 1995; and the second shall begin November 1, 1995
         and end on September 30, 1997.

2)       HAJV shall renovate suite 500 in accordance with the specifications to
         be agreed upon by both parties.  Both parties shall make their most
         diligent effort to complete such renovations by April 30, 1994.  HAJV
         shall pay no more than $3.80 per usable s.f. ($12,980.80) of the total
         cost of such renovation.  NCD shall pay the balance of the
         construction cost in equal monthly payments during the first period of
         lease.

3)       NCD shall pay to HAJV $2,700.00 per month as rent during the first
         period plus 1/18th of the additional build out described above.
         During the second period NCD shall pay $5,217.95 per month.  Neither
         of these amounts include sales tax which is in addition to these
         amounts.

4)       At the expiration of these two periods described above, NCD shall have
         the option to extend the term in accordance with the terms and
         conditions described in the original lease agreement.


This document shall become part of the original Lease Agreement, dated July 8,
1992, signed by these to parties.  This expansion space shall be governed by
the same terms and conditions contained in that particular Lease, except for
the modifications made above.


Agreed to this 28th day of February 1994:




/s/ Nelson Fernandez                               /s/ Ross White
------------------------------------------         ----------------------------
Horizon Associates Joint Venture, Landlord         Ross White Enterprises,
Horizon ANF, Inc., General Partner                      Inc., Tenant
Nelson Fernandez, Secretary/Treasurer              d/b/a National Computer
                                                        Distributors, Inc. 
                                                   Gregory White, President