<PAGE> 1

                                 EXHIBIT 10 (OO)

    PURCHASE/SALE AGREEMENT DATED AND EFFECTIVE DECEMBER 16, 1997 BETWEEN THE
   COMPANY, AS BUYER, AND CONTINENTAL EXECUTIVE PARKE, VERNON HILLS, ILLINOIS,
                              MADE ON MARCH 2, 1998

<PAGE> 2

Daniel B. Zoller
Arnstein & Lehr
120 South Riverside Plaza
Suite 1200
Chicago, Illinois 60606-3910


December 22, 1997


Mr. Harry Harczak
CDW Computer Centers, Inc.
200 N. Milwaukee Avenue
Vernon Hills, Illinois 60061


     RE: CONTINENTAL EXECUTIVE PARKE, VERNON HILLS, IL - LOTS 17, 89 AND 90

Dear Mr. Harczak:

         Enclosed for your files is a fully  executed  copy of the  Agreement of
Purchase and Sale and Joint Escrow Instructions for Parcel 17 and Parcels 89 and
90.

         Please note,  the Agreements  are  incorrectly  dated November 16, 1997
instead of December 16, 1997,  but the Seller has  confirmed in writing that the
correct  effective date for both Agreements is December 16, 1997. A copy of said
letter agreement is also enclosed for your files.

         Of course,  should you have any questions or comments,  please  contact
me.

                                                            Very truly yours,

                                                            /s/ Daniel B. Zoller
                                                            --------------------
                                                            Daniel B. Zoller

DBZ/ncr
Enclosure
Cc:      Mr. Tim Thompson (w/enclosures)
         Michael S. Tepper
221339_1

<PAGE> 3

Daniel B. Zoller
Arnstein & Lehr
120 South Riverside Plaza
Suite 1200
Chicago, Illinois 60606-3910


December 19, 1997


VIA FACSIMILE: (503) 624-7755
Nancy B. Murray, Esq.
c/o Pacific Realty Associates, L.P.
15350 S.W. Sequoia Pkwy.
Suite 300
Portlland, Oregon 97224


  RE:    AGREEMENT OF PURCHASE AND SALE AND JOINT ESCROW INSTRUCTIONS FOR LOTS 
         89 & 90, CONTINENTAL EXECUTIVE PARKE, VERNON HILLS,  IL; AND AGREEMENT
         OF PURCHASE AND SALE AND JOINT ESCROW INSTRUCTIONS FOR LOT 17 IN 
         CONTINENTAL EXECUTIVE PARKE, VERNON HILLS, IL


Dear Ms. Murray:

         Pursuant to our  telephone  conversation  this  afternoon,  while I was
reviewing  the  above-referenced  fully-executed  Agreements  that  we  received
yesterday  afternoon,  I noticed  that both  Agreements  are  erroneously  dated
November  16, 1997  instead of December  16,  1997.  Obviously  this was just an
oversight,  as your letter to Chicago Title dated  December 17, 1997  references
that the Agreements are dated December 16, 1997.

         The  purpose of this letter is to confirm  that the parties  agree that
the correct effective date for both Agreements is December 16, 1997 and that all
dates, including, but not limited to, the contingency dates set forth in Section
3 of each Agreement,  shall be based on the Agreements  being dated December 16,
1997.

         If the foregoing states your client's  understanding  and agreement,  I
would  appreciate  you  executing  a copy of this letter on behalf of the Seller
below,  and  returning  the same to me by  facsimile  today with the original to
follow by regular  mail.  If the  foregoing  is  inaccurate,  please  contact me
immediately.

         Your execution of this letter  agreement  shall be your  affirmation of
your  authority to act on behalf of your client to  effectuate  and confirm this
matter.

         Of course,  should you have any questions or comments,  please  contact
me.

                                                            Very truly yours,

                                                            /s/ Daniel B. Zoller
                                                            --------------------
                                                            Daniel B. Zoller

DBZ/ncr
Cc:      Michael S. Tepper


AGREED:

By: /s/ Nancy B. Murray
    ------------------- 
    Attorney for Seller

Date: December 19, 1997
221034_1

<PAGE> 4

                           Continental Executive Parke
                        Parcels 89 & 90, Vernon Hills, IL


                         AGREEMENT OF PURCHASE AND SALE
                          AND JOINT ESCROW INSTRUCTIONS


         THIS AGREEMENT OF PURCHASE AND SALE AND JOINT ESCROW INSTRUCTIONS (this
"AGREEMENT") is made and entered into as  of  this 16  day of November, 1997, by
and between CONTINENTAL  EXECUTIVE PARKE,  L.L.C., an Illinois limited liability
company  ("SELLER"),  and CDW COMPUTER  CENTERS,  INC., an Illinois  corporation
("BUYER").

1.       AGREEMENT OF PURCHASE AND SALE; DESIGNATION OF ESCROW HOLDER.

1.1. Subject to and on the terms and conditions herein set forth,  Seller hereby
agrees to sell,  assign and convey to Buyer, and Buyer hereby agrees to purchase
and acquire from Seller,  that real property  located in  Continental  Executive
Parke,  Village of Vernon Hills, Lake County,  Illinois,  known as Lots 2 and 3,
Continental  Executive Parke  Resubdivision  No. 17, including all appurtenances
thereto and improvements thereon (the "Property").

1.2.  The purchase and sale of the  Property  shall be  accomplished  through an
escrow (the  "ESCROW")  which  Seller has  established  or will  establish  with
Chicago Title  Insurance  Company (the "ESCROW  HOLDER") at 888 SW Fifth Avenue,
Portland, Oregon 97204, Attention: Diane Petterson (503 248-0955).

2.       CONSIDERATION; METHOD OF PAYMENT.

         The  purchase  price which  Buyer shall pay to Seller for the  Property
shall be Four Million Three Hundred Thousand  Sixty-Three  Dollars  ($4,300,063)
through Escrow at the Closing as follows:

2.1. Concurrently with its execution of this Agreement, Buyer shall deposit with
the Escrow  Holder a certified or  cashier's  check in the amount of Two Hundred
Fifteen  Thousand Dollars  ($215,000) (the "EARNEST MONEY DEPOSIT").  The Escrow
Holder   shall   immediately   deposit   the   Earnest   Money   Deposit   in  a
federally-insured  financial  institution  reasonably  satisfactory to Buyer and
Seller in an account in the name of Buyer.  All  interest  earned on the Earnest
Money  Deposit shall be and become a part of the Earnest Money Deposit and shall
be handled in the same  manner as the  Earnest  Money  Deposit as  provided  for
herein.

2.2.  Subject to the  provisions  of Section  3.4.6  hereof,  the balance of the
purchase  price  shall be  deposited  by Buyer in  Escrow  strictly  as and when
required under Section 10 hereof.

2.3. In the event Buyer  fails to deposit  the Earnest  Money  Deposit in Escrow
strictly as and when contemplated under Section 2.1 above, Seller shall have the
right at any time  thereafter to terminate this Agreement and all further rights
and obligations hereunder by giving written notice to Buyer.

                                       1

<PAGE> 5

2.4. In the event that Buyer fails to deposit the balance of the purchase  price
in Escrow  strictly as and when  contemplated  under  Section 2.2 above,  Seller
shall be entitled to retain the Earnest Money  Deposit as liquidated  damages as
more fully provided in Section 15 hereof.

3. CONDITIONS PRECEDENT TO BUYER'S AND SELLER'S OBLIGATIONS TO CLOSE.

3.1.  Set forth in Section 3.4 below are  certain  conditions  precedent  to the
obligation  of  Buyer  to  consummate  the  transaction   contemplated  by  this
Agreement.  Each such  condition must be satisfied or waived in writing by Buyer
or  deemed  satisfied  as  provided  in this  Section  3 before  Buyer  shall be
obligated to consummate this transaction.

3.2. Within the period specified below for each condition precedent, Buyer shall
give  written  notice to Seller  stating,  with  respect to each such  condition
precedent,  whether such condition is satisfied or remains  unsatisfied,  in the
reasonable  opinion of Buyer,  or is waived by Buyer.  With  respect to any such
condition  which  remains  unsatisfied,  Buyer  shall  specify in such notice in
reasonable  detail the reason therefor.  In the event that Buyer fails timely to
give such notice with respect to any such  condition,  such  condition  shall be
deemed to be satisfied.

3.3. In the event that Buyer gives timely notice that any condition precedent is
unsatisfied  as  provided  above,  Seller  shall  have  the  right,  but not the
obligation,  for a period  of ten (10)  days  after  receipt  of such  notice to
attempt to bring about the satisfaction of the specified condition. In the event
that Buyer fails  timely to give such  notice,  such  condition  shall be deemed
satisfied.  In the event that any condition  remains  unsatisfied as of the time
period  specified  below  with  respect  to such  condition  (or ten  (10)  days
thereafter  in the event  that  Seller  elects  to  attempt  to bring  about the
satisfaction  of such  condition  after notice from Buyer that such condition is
unsatisfied  as provided  above)  either party may terminate  this  Agreement by
giving  written  notice to the other party and the Escrow Holder  specifying the
unsatisfied  condition  or  conditions.  In the event of such  termination,  the
Escrow Holder shall terminate the Escrow and return the Earnest Money Deposit to
Buyer, and, except as otherwise  expressly  provided in this Agreement,  neither
party shall have any further rights or obligations  under this Agreement.  Buyer
and  Seller  shall each be  responsible  for  payment  to the  Escrow  Holder of
one-half of the Escrow fees and charges related to termination, if any.

3.4.  The  conditions   precedent  to  Buyer's  obligation  to  consummate  this
transaction are the following:

3.4.1.  Within ten (10) days after receipt of a current Preliminary Title Report
or Commitment for the Property (the "TITLE  REPORT") and copies of all documents
constituting  exceptions to title of record which are specified in Schedule B of
the Title Report, Buyer shall have approved or disapproved title to the Property
as shown in the Title  Report.  Unless  Seller has already done so, Seller shall
order the Title  Report and  documents  promptly  after full  execution  of this
Agreement.

3.4.2.  Within  twenty (20) days after  receipt of a current  ALTA survey of the
Property,  Buyer shall have approved or  disapproved  the survey and all matters
disclosed  thereby.  Unless  Seller has already done so,  Seller shall order the
survey promptly after full execution of this Agreement.

                                       2

<PAGE> 6

3.4.3. Within sixty (60) days after the date of this Agreement, Buyer shall have
conducted or obtained,  at its sole cost and expense,  all feasibility  analyses
and surveys (in  addition to the survey  provided by Seller  pursuant to Section
3.4.2 above),  tests,  audits and studies and shall have conducted such physical
and other  inspections  as Buyer deems  necessary to enable Buyer to approve the
purchase of the property and the physical  condition of the Property,  including
without limitation the structural condition of any improvements,  all zoning and
land use  matters,  and the soils and ground water  conditions  in and about the
Property.

                           IN THIS REGARD,  SELLER HEREBY  REPRESENTS THAT THERE
MAY  BE   ON  THE  PROPERTY   UNDERGROUND  STORAGE   TANKS,  ASBESTOS-CONTAINING
MATERIALS,  AND/OR  TRANSFORMERS  OR OTHER EQUIPMENT CONTAINING  POLYCHLORINATED
BIPHENYLS  (PCB's), AND/OR  OTHER HAZARDOUS MATERIALS  (AS  DEFINED  IN  SECTION
4.3  BELOW),  ANY OF  WHICH  MAY  EXIST IN  CONJUNCTION  WITH  ATTENDANT SOIL OR
GROUND WATER CONTAMINATION.

                           Buyer and its agents  may  enter  onto  the  Property
to make such  inspections,  audits, studies,  tests and surveys thereof as Buyer
deems reasonably necessary to bring about the  satisfaction  of  this condition;
provided,  however,  that no grading shall be done, no trees or bushes  shall be
cut and  Buyer  shall not  conduct  any  drilling  or  install any wells without
Seller's  prior  written  consent;  and provided, further, that Buyer shall have
provided Seller with a certificate of  liability  insurance  naming  the  Seller
as an  additional  insured  and  with coverages of not less than  $3,000,000 for
property  damage and death or injury (combined  single limit).  Buyer shall keep
in strict confidence the results of any such inspections, audits, studies, tests
and surveys, and shall disclose the results  thereof  only if and as required by
law or legal process.  Buyer shall keep the Property free and clear of any liens
resulting  from any such entry onto the Property;  Buyer shall repair any damage
to the Property resulting from such entry;  and Buyer  shall defend  Seller with
counsel  reasonably  satisfactory  to  Seller and  protect,  hold  harmless  and
indemnify  Seller  from  and against  any  and  all  claims,  demands,  damages,
liabilities or costs of any kind  whatsoever (including attorneys' fees) arising
out of or connected with any such entry onto the Property or  the  disclosure of
the results of any such  inspections,  audits, studies,  tests  and  surveys  in
contravention  of  Buyer's confidentiality obligations contained in this Section
3.4.3. In the event Buyer terminates this  Agreement  for failure of a condition
precedent  as provided in this Section 3, Buyer shall deliver a copy of all such
surveys,  tests,  audits and studies and  the  results  of any and all  physical
inspections  to  Seller  as a  condition  precedent  to Buyer's  right to obtain
disbursement  of Buyer's  Earnest  Money Deposit.  The  foregoing  covenants  of
Buyer shall  survive and be enforceable following consummation or termination of
this Agreement.

3.4.4.  As of the Closing (as  defined in Section 8 hereof),  Seller  shall have
given no notice to Buyer stating that Seller has obtained knowledge or notice of
any fact or facts which would make any  representation or warranty of Seller set
forth in Section 5 hereof untrue or misleading in any material respect.

                                       3

<PAGE> 7

3.4.5.  As of the Closing (as  defined in Section 8 hereof),  Seller  shall have
performed  each and all of the  obligations to be performed by Seller under this
Agreement prior to the Closing.

3.4.6.  A  condition   precedent  to  Seller's   obligation  to  consummate  the
transaction contemplated by this Agreement shall be that We'll Take Care of You,
L.L.C.,  Buyer or an affiliate of Buyer shall have entered into a separate  sale
agreement for the purchase  from Seller of the real property  known as Parcel 17
in Continental Executive Parke, the closing on which the parties anticipate will
occur simultaneously with or after Closing under this Agreement.  Seller, in its
sole discretion, may elect to waive this condition prior to or at Closing.

4.       SELLER'S DISCLAIMER WITH RESPECT TO PHYSICAL CONDITION OF PROPERTY  AND
         APPLICABLE  LAWS  AND  REGULATIONS;  BUYER  TO  TAKE  PROPERTY "AS IS";
         RESTRICTIVE USE; BUYER'S RELEASE AND INDEMNITY RE: ENVIRONMENTAL HAZARD
         RISKS.

4.1. Except as provided in Section 3.4.3 above and Section 5 below, Seller makes
no representation or warranty  whatsoever with respect to the physical condition
of the Property. Buyer acknowledges that:

4.1.1.  Buyer  has  entered  into this  Agreement,  and if Buyer  purchases  the
Property  Buyer  will do so,  on the basis of its own  investigation  of the all
aspects of the Property  including  without  limitation all physical  conditions
thereof,  including any building and other improvements and the soils and ground
water conditions of the Property and its immediate environs; and

4.1.2.  Buyer will acquire the Property in an "AS IS" condition and shall assume
the risks that adverse  physical or other  conditions may not have been revealed
by its investigation.

4.2.  Seller makes no  representation  or warranty  whatsoever as to existing or
proposed governmental laws or regulations applicable to the Property,  including
without  limitation  laws  or  regulations  concerning  zoning  or  land  use or
Hazardous  Materials (as defined in Section 4.3 below).  Buyer acknowledges that
it has entered into this  Agreement,  and if Buyer  purchases the Property Buyer
will  do  so,  on  the  basis  of  its  own  review  and  investigation  of  the
applicability  and effect of such laws and  regulations,  and Buyer  assumes the
risks that adverse matters may not have been revealed by its investigation.

4.3.  Effective  as of Close of Escrow (as  defined  in Section 8 below),  Buyer
hereby waives, releases, acquits and forever discharges Seller and its officers,
directors, partners, employees, agents, and any other person acting on behalf of
Seller, from and against any and all claims, actions, causes of action, demands,
rights, damages, costs, expenses or compensation whatsoever, direct or indirect,
known or unknown, foreseeable or unforeseeable, which Buyer now has or which may
arise in the future on account of or in any way growing out of or connected with
the  presence  in or on the  Property,  or any  building  or  other  improvement
thereon,  or under the surface of the Property,  of  underground  storage tanks,
asbestos-containing  materials,   transformers  or  other  equipment  containing
polychlorinated  biphenyls,  or any  hazardous  or  toxic  waste,  substance  or
material  as defined in any  Federal,  State or Local law,  rule,  ordinance  or

                                       4

<PAGE> 8

regulation  which  may  now  or  hereafter  be  applicable  (collectively,   the
"HAZARDOUS MATERIALS").  Buyer hereby agrees to protect,  defend,  indemnify and
hold Seller and its officers,  directors,  partners,  employees, agents, and any
other person acting on behalf of Seller,  free and harmless from and against any
and all losses,  actual or  consequential  damages  whether  foreseeable or not,
punitive  damages,  fines,  liabilities,  costs  (including costs of clean-up or
other remediation and required  studies),  interest,  attorneys' fees (including
such fees and expenses incurred in enforcing this indemnity),  suits,  causes of
action,  legal or administrative  proceedings,  demands,  or claims  (including,
without limitation,  claims for personal injury) made, threatened or asserted by
any person,  party or  governmental  entity or agency by reason of or in any way
connected  with the  presence in or on the  Property,  or any  building or other
improvement  thereon,  or  under  the  surface  of the  Property,  of  Hazardous
Materials.  The foregoing covenants of Buyer shall survive and be enforceable in
accordance with their terms following the  consummation of this  transaction and
shall not be merged with or into the deed  delivered by Seller to Buyer  through
Escrow at Close of Escrow.

4.4.  Promptly after the mutual  execution of this  Agreement,  Seller will make
available to Buyer,  for Buyer's  review and  photocopying  at its sole expense,
during normal business hours, all environmental and engineering documents in the
possession of Seller relating to the Property (excluding  appraisals,  financial
information  confidential  to  Seller  and  its  partners,  and  attorney-client
privileged  communications,  if any).  Such  file  review  may  take  place at a
mutually-convenient  location  to be  coordinated  at  Buyer's  request by Stout
Development  (Robert  Guarnaccio) at 847-247-1183.  Seller does not warrant (and
Buyer releases  Seller from any  responsibility  or liability for) the accuracy,
fitness or  reliability  of any such  documentation  or any  recommendations  or
conclusions  contained therein. All documentation copied from Seller's files and
the information contained therein shall be treated as confidential and shall not
be revealed or otherwise  disclosed  by Buyer except (i) with the prior  written
consent of Seller,  (ii) as required  pursuant to law,  court order or subpoena,
(iii) as may be  reasonably  required by Buyer's  lender  [provided  such lender
treats  such  documentation  and  information  as  confidential,  subject to the
exceptions  stated  in the  foregoing  clauses  (i) and  (ii)],  or (iv) for the
exercise  by Buyer of any  remedy  hereunder.  In  addition,  in the  event  the
transaction  contemplated by this Agreement does not close, Buyer shall promptly
return to Seller all such  documentation  without  keeping  any  copies  thereof
except  to  the  extent  reasonably  necessary  in  connection  with  any  legal
proceeding pertaining to the Property involving Buyer.

5.       REPRESENTATIONS AND WARRANTIES OF SELLER.

5.1. Seller makes the following representations and warranties, each of which is
true in all  respects  as of the date hereof and shall be true as of the Closing
except to the extent  that  Seller  obtains  knowledge  or notice of any fact or
facts that would make any representation or warranty untrue or misleading in any
material  respect and discloses  such fact or facts to Buyer in writing prior to
the Closing:

5.1.1. Seller is duly organized, validly existing and in good standing under the
laws of the State of Illinois.  


                                       5

<PAGE> 9

5.1.2. This Agreement has been duly executed and  delivered by  Seller  and is a
valid and binding obligation of Seller, enforceable against Seller in accordance
with its terms.

5.1.3. To Seller's actual knowledge,  without inquiry,  there is no condemnation
or eminent domain proceeding pending or threatened against the Property.

5.1.4. To Seller's actual  knowledge,  without  inquiry,  there is no litigation
pending or  threatened  which affects the Property or that would or might affect
the transaction  contemplated  hereby or the ability of Seller to satisfy all of
its obligations hereunder.

5.1.5.  Seller has not  received  any written  notification  from any  insurance
company,   Board  of  Insurance   Underwriters  or  any  governmental  authority
specifying  any  non-compliance  of the  Property  or any portion  thereof  with
applicable codes, statutes, ordinances or regulations that remains uncured.

5.1.6.  Seller is not a foreign  person as  defined  in  Internal  Revenue  Code
Section 1445(f)(3).

5.1.7.  There are no leases or  tenancies  or service  contracts  affecting  the
Property that will not be terminated prior to or as of Closing.

5.1.8.  There are no  outstanding  contracts for the purchase of the Property or
any portion thereof, and neither the Property nor any portion thereof is subject
to any other contracts of sale or option.

5.2.  Buyer  and  Seller  each  specifically  acknowledge  and  agree  that  all
references  contained  in this  Agreement to  "Seller's  knowledge"  or words of
similar  import (i) shall refer to the actual  personal  knowledge of F. Michael
Nugent ("Mr. Nugent"); (ii) shall in no case refer to the actual or constructive
knowledge   of  any  other   employee,   agent,   officer,   director  or  other
representative of Seller or any investment advisor, attorney or other contractor
or   representative   of  Seller   (together  with  Mr.   Nugent,   the  "Seller
Representatives");  and (iii)  shall in no case impose upon Seller or any Seller
Representative any duty or obligation to verify any representation,  warranty or
statement contained in this Agreement,  in any exhibit attached hereto or in any
document, certificate or statement to be delivered by Seller to Buyer hereunder,
or to otherwise  investigate  the facts or  circumstances  relating or otherwise
pertinent thereto.

5.3.  In the  event  of a breach  of any of the  foregoing  representations  and
warranties,  Buyer's  sole right and remedy  with  respect  to such  breach,  in
addition to the right to attorney fees as allowed by Section 18 hereof, shall be
to compel Seller to take such action at Seller's  expense as may be necessary to
cure the breach  (and in no event  will  Buyer  have any right to  rescind  this
transaction  or seek  consequential  damages).  Said  right  of  Buyer  (and the
concomitant obligation of Seller) following any such breach of representation or
warranty shall survive the consummation of this Agreement.

                                       6

<PAGE> 10

6.       REPRESENTATIONS AND WARRANTIES OF BUYER.

         Buyer hereby makes the following  representations and warranties,  each
of which is true in all  respects  as of the date hereof and shall be true as of
the Closing  except to the extent that Buyer obtains  knowledge or notice of any
fact or facts  that  would  make  any  representation  and  warranty  untrue  or
misleading in any material respect and discloses such fact or facts to Seller in
writing prior to the Closing:

6.1. Buyer is duly  organized,  validly  existing and in good standing under the
laws of the State of Illinois.

6.2. The persons  executing  this Agreement on behalf of Buyer are authorized to
do so and, upon execution by such parties,  this Agreement  shall be a valid and
binding  obligation of Buyer,  enforceable  against Buyer in accordance with its
terms.

7.       BUYER'S TITLE INSURANCE POLICY.

         Buyer's  title to the Property at Close of Escrow shall be evidenced by
the issuance of a standard (or, at Buyer's option, an extended coverage) owner's
policy of title insurance (the "BUYER'S TITLE INSURANCE  POLICY") at the Closing
in favor of Buyer or its nominee  insuring that fee simple title to the Property
is  vested  in  Buyer or its  nominee,  subject  only to (a) the lien to  secure
payment of real estate taxes and assessments not delinquent;  (b) the exceptions
to title  approved  by Buyer  pursuant to Section 3 of this  Agreement;  (c) all
matters  that  would be  disclosed  by a  physical  inspection  or survey of the
Property  (provided  that  this  exception  shall be  deleted  from an  extended
coverage  owner's title  insurance  policy) or that are actually known to Buyer;
(d) any additional exceptions or matters created by Buyer, its agents, employees
or  authorized  representatives;   (e)  the  printed  conditions,  restrictions,
exceptions,  stipulations  and  other  provisions  contained  in  Buyer's  Title
Insurance  Policy;  and  (f)  such  other  exceptions  as  Buyer,  in  its  sole
discretion, may approve in writing. All matters concerning title to the Property
shall  merge in the deed to be  delivered  by  Seller  to Buyer at the  Closing.
Seller's  obligation  with respect to the  condition of title to the Property at
the Closing shall be completely satisfied and fulfilled upon the issuance by the
Escrow Holder of Buyer's  Title  Insurance  Policy.  Absent fraud on the part of
Seller, in the event of any defect in or other matter adversely  affecting title
to the Property which appears following the Closing,  Buyer shall look solely to
Buyer's Title  Insurance  Policy to obtain any redress or relief for any damages
incurred by Buyer as a result of said defect or matter and Buyer hereby releases
Seller from any and all cost, damage, claim or liability arising out of any such
defect or matter.

8.       CLOSING DATE; CLOSE OF ESCROW.

8.1. Unless this Agreement has been terminated  pursuant to Section 3 hereof and
unless  deferred  as  provided  in Section 13 hereof,  the  consummation  of the
purchase  and sale of the  Property  in  accordance  with  this  Agreement  (the
"CLOSING")  shall  take place as soon as  possible  on the date which is fifteen
(15) days after the last of the  conditions  precedent  set forth in Section 3.4
hereof has been  satisfied  or waived by Buyer,  unless such date is a Saturday,

                                       7

<PAGE> 11

Sunday or business  holiday,  in which event the Closing shall take place on the
next regularly  scheduled business day (the "CLOSING DATE") at the office of the
Escrow Holder or as otherwise agreed to by the parties.  "CLOSE OF ESCROW" shall
mean the  recordation of the deed vesting title to the Property in Buyer and the
disbursement  to Seller in accordance  with its  instructions of the proceeds in
Escrow in Seller's account at the Closing. 8.2. At the Closing the Escrow Holder
shall  disburse to Seller,  in such manner and to such  account as Seller  shall
specify in a separate  written  instruction  to the Escrow  Holder,  immediately
available  funds in the  amount  of the  purchase  price  paid by Buyer  for the
Property as specified in Section 2 hereof  (increased or decreased,  as the case
may be, by the net  amount of the  credits  and  debits to  Seller's  account at
Closing  made  by the  Escrow  Holder  in  accordance  with  Section  11 of this
Agreement).

9.       SELLER'S CLOSING OBLIGATIONS.

9.1.  By such time and date as may be  required  by the Escrow  Holder to permit
Closing to occur on or by the Closing Date, Seller shall deposit in Escrow:  (i)
a duly executed and  acknowledged  special  warranty deed or equivalent  for the
conveyance of the Property to Buyer in accordance  with this  Agreement;  (ii) a
quitclaim and/or  assignment of any licenses and permits affecting the Property;
(iii) a certification executed by Seller confirming that the representations and
warranties  contained  in Section 5 above are true and correct as of the date of
Closing;  (iv) any  disclosure  document  as defined in and if  required  by the
Illinois Responsible Property Transfer Act; (v) any other documents, instruments
or things  required  by this  Agreement  to be  delivered  by Seller to Buyer or
deposited  by Seller  into  Escrow  at the  Closing;  and (vi) any  supplemental
instructions  which the Escrow  Holder may require for the  consummation  of the
transaction in accordance with this Agreement.

9.2.  By such time and date as may be  required  by the Escrow  Holder to permit
Closing  to  occur on or by the  Closing  Date,  Seller  shall  deposit  cash or
immediately  available  funds  in  Escrow  in  such  amount  as (or  make  other
arrangements  satisfactory to the Escrow Holder) to cover any net obligations of
Seller  arising out of the  prorations  and  apportionment  of Closing  costs as
specified in Section 11 of this Agreement as may be reasonably  estimated by the
Escrow Holder.

10.      BUYER'S CLOSING OBLIGATIONS.

10.1.  By such time and date as may be required  by the Escrow  Holder to permit
Closing to occur on or by the Closing Date,  Buyer shall deposit in Escrow:  (i)
any instruments,  documents or things required by this Agreement to be delivered
by Buyer to  Seller  or  deposited  into  Escrow  at the  Closing;  and (ii) any
supplemental  instructions  which the Escrow Holder may  reasonably  require for
consummation of the transaction in accordance with this Agreement.

10.2.  By such time and date as may be required  by the Escrow  Holder to permit
Closing to occur on or by the  Closing  Date,  Buyer shall  deposit  immediately
available funds (e.g., by cashier's check or wire transfer) into such account of
the Escrow  Holder as shall be specified by the Escrow  Holder in the sum of the
following amounts:

                                       8

<PAGE> 12

10.2.1.  The balance of the purchase price as specified in Section 2.2 hereof; 
and

10.2.2. Such amount as may be reasonably estimated by the Escrow Holder to cover
any net obligations of Buyer arising out of the prorations and  apportionment of
closing costs pursuant to Section 11 of this Agreement.

11.      CLOSING PRORATIONS; APPORTIONMENT OF CLOSING COSTS.

         Current real property taxes and assessments,  any rents,  utilities and
common  area  maintenance  charges  shall be  prorated as of midnight of the day
preceding the Closing Date. If the amount of the current real property  taxes is
not then  ascertainable,  the  proration  thereof  shall be on the  basis of the
amount of 110% of the most recent  ascertainable  real  estate tax bill.  Seller
shall pay any state or county  transfer taxes,  the title insurance  premium for
the  Buyer's  Title  Insurance  Policy  and the  cost for the  survey  delivered
pursuant to Section 3.4.2 above.  Buyer shall pay the cost of recording the Deed
and any of Buyer's  financing  documents and the cost of all endorsements to the
Buyer's Title  Insurance  Policy beyond those  customarily  given in an extended
coverage  owner's title  insurance  policy.  All other Closing costs,  including
without  limitation  the escrow  fee,  shall be  apportioned  to and paid by the
parties equally.

12.      COMMISSIONS.

12.1.  Seller shall pay through Escrow at the Close of Escrow and conditional on
the Close of Escrow a  commission  in the  amount  of two and  one-half  percent
(2.5%) of the purchase  price payable to  Paine/Wetzel  Associates,  Inc., and a
commission  in the amount of two and  one-half  percent  (2.5%) of the  purchase
price payable to Korman & Lederer.

12.2.  Buyer and  Seller  hereby  acknowledge  that no  broker's  commission  or
finder's  fee other than that  referred  to Section  12.1 above is payable  with
regard to the transaction  contemplated by this Agreement;  and Buyer and Seller
(each being hereinafter referred to in this Section 12 as the "Indemnitor") each
agrees to defend with  counsel  reasonably  satisfactory  to the other party and
indemnify  the other  party from and  against all  liability,  claims,  actions,
causes of action, suits, demands,  damages, or costs of any kind arising from or
connected  with any broker's or finder's fee or commission or charge  claimed to
be due any person  arising  from the  Indemnitor's  conduct with respect to said
transaction,  other than the commission provided for in Section 12.1 above. This
obligation shall survive and be enforceable following the Closing or termination
of this Agreement.

13.      DAMAGE OR DESTRUCTION; CONDEMNATION.

         In the event of loss or of damage to the building improvements included
within  the  Property  by fire or other  casualty  prior to Close of  Escrow  (a
"Casualty"),  or in the event a proceeding is instituted or threatened  prior to
Close of Escrow for the taking of all or any portion of the  Property  under the
power of  eminent  domain (a  "Taking"),  Buyer  shall  have the right by giving

                                       9

<PAGE> 13

written notice to Seller and the Escrow Holder within thirty (30) days after the
date of receipt of written notice of any such Casualty or Taking,  either to (i)
consummate  the  purchase  and sale of the  Property  in  accordance  with  this
Agreement  (in which event Seller  shall  deliver to Buyer at Close of Escrow an
assignment reasonably  satisfactory in form and substance to Buyer of all of the
right,  title and interest,  if any,  which Seller may have in (A) the insurance
payable under all insurance policies kept or maintained by Seller as a result of
or in  connection  with such Casualty and (B) the award payable by reason of the
Taking  and,  concurrently  therewith,  deposit  cash in Escrow for Buyer in the
amount of any and all such proceeds and award  theretofore  received by Seller);
or (ii)  terminate  this  Agreement  effective  as of the date  such  notice  of
termination  is given  to  Seller.  The  Closing  Date  shall  be  deferred,  if
necessary,  to permit  Buyer to have the  thirty  (30)-day  period  following  a
Casualty or Taking to make the election specified hereinabove.

         In the event of any such  termination the Escrow Holder shall forthwith
terminate the Escrow.  Seller and Buyer shall each be responsible for payment to
the Escrow  Holder of one-half  (1/2) of the Escrow fees and charges  related to
termination, if any. Provided Buyer shall have given a copy to Seller of any and
all surveys,  tests, audits and studies made by or for Buyer pursuant to Section
3.4.3 of this Agreement, upon termination of this Agreement as provided above in
this Section 13, the Escrow  Holder shall  forthwith  disburse  Buyer's  Earnest
Money Deposit (and any interest earned thereon) to Buyer (less Buyer's share, if
then unpaid, of the Escrow fees and charges related to termination, if any).

14.      NOTICES.

         Any notice, demand, approval,  consent, or other communication required
or desired to be given  under this  Agreement  shall be in writing  and shall be
given  personally,  by messenger  (including  overnight  delivery service) or by
certified  mail,  return receipt  requested,  in each case with postage or other
charges prepaid, directed to the party involved at the address indicated below:

To Seller:         Continental Executive Parke, L.L.C.
                   c/o Pacific Realty Associates, L.P.
                   Attn:  Nancy B. Murray, Esq.
                   15350 S.W. Sequoia Pkwy., #300
                   Portland, OR  97224

                                       10

<PAGE> 14

To Buyer:          CDW Computer Centers, Inc..
                   Attn:  Mr. Michael P. Krasny
                   1020 East Lake Cook Road
                   Buffalo Grove, IL 60087-7193

                   And To:

                   Michael Tepper, Esq.
                   Arnstein & Lehr
                   120 Riverside Plaza, Suite 1200
                   Chicago, IL 60606-3913

         Any notice,  demand,  approval,  consent or other  communication  given
personally  or by  messenger  shall be  deemed  to have  been  given on the date
delivered and any notice, demand, approval, consent or other communication given
by mail shall be deemed to have been given when three (3) days have elapsed from
the date it was sent by certified United States mail, return receipt  requested,
postage prepaid,  addressed to the party to be served at said address or at such
other address of which that party may have given notice under the  provisions of
this Section.

15.      LIQUIDATED DAMAGES.

15.1.  SELLER AND BUYER  ACKNOWLEDGE THAT SELLER IS VERY DESIROUS OF CLOSING THE
TRANSACTION  CONTEMPLATED  HEREBY  WITHIN  THE TIME  FRAME  ESTABLISHED  BY THIS
AGREEMENT,  AND THAT SUBSTANTIAL DAMAGES WILL BE SUFFERED BY SELLER IN THE EVENT
THAT THE PURCHASE AND SALE OF THE PROPERTY  PROVIDED FOR IN THIS  AGREEMENT DOES
NOT CLOSE WITHIN SUCH TIME FRAME DUE TO BUYER'S  DEFAULT  UNDER THIS  AGREEMENT.
SELLER  AND  BUYER  FURTHER   ACKNOWLEDGE   THAT  SELLER  WILL  BE  ENTITLED  TO
COMPENSATION  IF THE  PURCHASE  AND SALE OF THE  PROPERTY  DOES NOT CLOSE DUE TO
BUYER'S DEFAULT. WITH THE FLUCTUATION IN LAND VALUES, THE UNPREDICTABLE STATE OF
THE ECONOMY AND OF GOVERNMENTAL  REGULATIONS,  THE  FLUCTUATING  MARKET FOR REAL
ESTATE AND REAL ESTATE  LOANS OF ALL TYPES,  AND OTHER  FACTORS  WHICH  DIRECTLY
AFFECT THE VALUE AND MARKETABILITY OF THE PROPERTY,  THE PARTIES REALIZE THAT IT
WOULD BE EXTREMELY  DIFFICULT AND  IMPRACTICABLE,  IF NOT IMPOSSIBLE,  AS OF THE
SIGNING OF THIS AGREEMENT,  TO ASCERTAIN WITH ANY DEGREE OF CERTAINTY THE EXTENT
OF  DAMAGES  TO  SELLER  IN THE  EVENT  OF  BUYER'S  DEFAULT  OR THE  AMOUNT  OF
COMPENSATION  SELLER  SHOULD  RECEIVE IN THE EVENT THAT THE PURCHASE AND SALE OF
THE PROPERTY  PROVIDED IN THIS AGREEMENT DOES NOT CLOSE DUE TO BUYER'S  DEFAULT.
ACCORDINGLY, THE PARTIES HEREBY AGREE THAT A REASONABLE ESTIMATE OF SUCH DAMAGES
OR SUCH  COMPENSATION,  AS THE CASE MAY BE, IS THE AMOUNT OF THE  EARNEST  MONEY
DEPOSIT, NAMELY, $215,000, AND ANY INTEREST EARNED THEREON.

                                       11

<PAGE> 15

15.2. THE PARTIES HEREBY AGREE THAT IF BUYER DEFAULTS UNDER THIS AGREEMENT, THEN
SELLER SHALL BE ENTITLED TO RECOVER  FROM BUYER THE AMOUNT OF THE EARNEST  MONEY
DEPOSIT, NAMELY THE SUM OF $215,000, PLUS ADDITIONAL AMOUNTS REQUIRED BY SECTION
3.4.6  ABOVE  WITH  ALL  INTEREST  EARNED  THEREON,  AS  LIQUIDATED  DAMAGES  OR
COMPENSATION,  AS THE CASE MAY BE,  UNDER THIS  AGREEMENT  AND SUCH  RECOVERY OF
$215,000,  WITH ALL  INTEREST  EARNED  THEREON  SHALL BE THE SOLE AND  EXCLUSIVE
REMEDY OF OR COMPENSATION TO SELLER,  AS THE CASE MAY BE, AS A RESULT OF BUYER'S
DEFAULT UNDER THIS  AGREEMENT,  EXCEPT AS SET FORTH IN THE LAST SENTENCE OF THIS
SECTION 15. NOTWITHSTANDING THE FOREGOING,  NOTHING CONTAINED HEREIN SHALL LIMIT
THE REMEDIES  SELLER SHALL HAVE TO ENFORCE ANY RIGHTS IT HAS AGAINST BUYER UNDER
THE PROVISIONS OF SECTIONS 3.4, 12 or 18.

                          /s/DWR
--------------            --------------
Buyer's initials          Seller's initials


15.3.  In the event of Seller's  default  hereunder  after the  satisfaction  or
waiver of all  conditions  precedent  set forth in  Section 3 hereof,  Buyer may
either (i) terminate  this  Agreement,  in which event the Earnest Money Deposit
shall be immediately refunded to Buyer, or (ii) enforce the specific performance
of this Agreement,  including  Seller's  obligation to transfer ownership of the
Property  to Buyer,  but in no event  will  Buyer be  entitled  to  punitive  or
consequential damages, if any, resulting from such default.

16.      INTEGRATED AGREEMENT; MODIFICATIONS; WAIVERS.

         This Agreement  constitutes  the entire  agreement  between the parties
hereto with  respect to the subject  matter  hereof and  supersedes  any and all
prior representations,  understandings and agreements,  whether written or oral.
No supplement,  modification  or waiver of any provision of this Agreement shall
be binding  unless  executed  in writing  by the party to be bound  thereby.  No
waiver  of any of the  provisions  of this  Agreement  shall be  deemed or shall
constitute a waiver of any other provision hereof (whether or not similar),  nor
shall such waiver  constitute a continuing  waiver  unless  otherwise  expressly
provided.

17.      TIME OF ESSENCE AND HOLIDAYS.

         Time is of the essence of each and every provision hereof. If the final
date of any  period of time set forth  herein  occurs on a  Saturday,  Sunday or
legal holiday,  then in such event,  the expiration of such period of time shall
be postponed to the next day which is not a Saturday, Sunday or legal holiday.

                                       12

<PAGE> 16

18.      ATTORNEYS' FEES.

         In the  event  either  party  brings  an  action at law or in equity to
enforce  or  interpret  or  seek  redress  for  breach  of this  Agreement,  the
prevailing party in such action shall be entitled to its litigation expenses and
reasonable  attorneys'  and witness  fees in  addition to all other  appropriate
relief,  at trial, on appeal,  or on any petition for review.  The provisions of
this Section 18 shall survive Closing.

19.      ASSIGNMENT; INUREMENT.

         Either party hereto may assign its  respective  rights and  obligations
hereunder,  in whole or in part,  without the prior written consent of the other
party hereto,  provided that such  assignment  shall be in writing and a copy of
such assignment shall be delivered  promptly to the other party hereto, any such
assignee shall asume all  obligations of the assignor  arising after the date of
the  assignment,  and the  assignor  of such  interest  shall not be released of
liability  hereunder.  Any assignment  without meeting such conditions  shall be
deemed  null and  void.  Subject  to and  without  limiting  the  preceding  two
sentences, this Agreement and every provision hereof shall bind and inure to the
benefit  of  the   parties   hereto  and  their   respective   heirs,   personal
representatives, successors and assigns.

20.      GOVERNING LAW.

         This Agreement shall be construed and interpreted and the rights of the
parties determined in accordance with the laws of the State of Illinois.

21.      COVENANTS OF COOPERATION.

         Seller and Buyer each agree to cooperate with each other and to execute
such  additional  documents  and  instruments,   including  supplemental  escrow
instructions,  as may be  reasonably  required  to  consummate  the  transaction
contemplated hereby.

22.      HEADINGS AND CAPTIONS.

         The headings and  captions of the  sections of this  Agreement  are for
convenience of reference only and shall not affect the meaning or interpretation
of this Agreement or any provision hereof.

23.      CONDITION TO EFFECTIVENESS OF AGREEMENT.

         This  Agreement  shall  not be  binding  or  effective  until  properly
executed and delivered by both Seller and Buyer.

                                       13

<PAGE> 17

24.      GENDER AND NUMBER.

         As used in this  Agreement,  the neuter shall  include the feminine and
masculine,  the singular shall include the plural,  and the plural shall include
the singular, except where expressly provided to the contrary.

25.      SEVERABILITY.

         In the event that any paragraph,  section,  sentence,  clause or phrase
contained  in  this  Agreement  becomes  or is held by any  court  of  competent
jurisdiction to be illegal, null or void or against public policy, the remaining
paragraphs,  sections, sentences, clauses or phrases contained in this Agreement
shall not be affected thereby.

26.      COUNTERPARTS.

         This  Agreement  may be executed in one or more  counterparts,  each of
which shall be deemed an original,  but all of which together  shall  constitute
one and the same  instrument.  This Agreement or any counterpart may be executed
and delivered by facsimile transmission with an executed hard copy to follow.

27.      EXHIBITS.

         All Exhibits  attached to, and  referenced in this Agreement are hereby
incorporated into, and shall be deemed a part of this Agreement.

28.      JOINT AND SEVERAL OBLIGATIONS.

         If more  than one  person  or  entity  is  included  within  the  party
designated  hereinabove as Buyer,  each and all of the obligations  imposed upon
such party under this  Agreement  shall be the joint and several  obligations of
each of such persons or entities.

29.      EVIDENCE OF DUE AUTHORIZATION.

         Each party  hereby  agrees,  within  ten (10) days  after  receipt of a
written  request  from the other  party,  to  furnish  to the other  party  such
evidence as shall  reasonably  establish that the execution of this Agreement by
the party  furnishing  such  evidence and the  performance  by such party of its
obligations  hereunder have been duly  authorized and that the person or persons
executing  this  Agreement  and any  document  or  instrument  pursuant  to this
Agreement has been duly authorized and empowered to do so.

30.      NO RECOURSE.

         Notwithstanding  anything to the contrary set forth in this  Agreement,
Buyer  shall  look  solely  to the  assets  of Seller  for  satisfaction  of any
liability  of Seller in respect  hereof and will not seek  recourse  against the
partners of Seller, or either of them, or their respective officers,  directors,
shareholders, employees, agents, or any of them, or any of their personal assets
for such satisfaction.

                                       14

<PAGE> 18

31.      ROADWAY IMPROVEMENTS; MUTUAL RELEASE

         Buyer and Seller are parties to that  Purchase/Sale  Agreement dated as
of February 12, 1996, pursuant to which Buyer purchased from Seller the property
known as Parcels 72, 73, 80 and 81 within Continental  Executive Parke (the "CDW
Contract").  Part of the consideration for the purchase and sale of the Property
pursuant  to this  Agreement  is a mutual  release of Buyer and Seller  from the
obligation to construct  certain Roadway  Improvements and other  obligations as
described  in  Section  18 and  any  related  provisions  of the  CDW  Contract.
Accordingly,  upon Closing under this Agreement, Buyer and Seller agree that the
obligations  of the parties in Section 18 and any related  provisions of the CDW
Contract shall terminate and be of no further force and effect,  and the parties
shall be deemed to have  released  each  other  from all such  obligations.  The
parties  agree  that  the CDW  Contract  is  hereby  modified  by the  foregoing
termination  and  release and agree to execute  such  additional  documents  and
instruments  as  either  may  reasonably   require  to  further   evidence  such
modification  and release.  In addition,  effective at Closing,  Buyer expressly
assumes  and  agrees to  satisfy,  at its sole  expense,  any  requirements  for
development  on the  Property  imposed by the  Village of Vernon  Hills or other
governmental   agency  with  jurisdiction,   including  without  limitation  the
requirements  under that  planned  unit  development  approved by the Village of
Vernon Hills as Ordinance  No. 639 dated March 10, 1988 and any other  ordinance
or  resolution  of the  Village of Vernon  Hills  affecting  the  Property,  and
including  without  limitation the construction of Parkeview Drive and/or a pond
on that  portion of the  Property  known as Parcel 90 (also  described as Lot 3,
Continental  Executive  Parke  Resubdivision  No. 17) and any other  storm water
management  requirements for the Property.  This provision shall survive Closing
under this Agreement.

                                       15

<PAGE> 19


         IN WITNESS WHEREOF,  the parties hereto have executed this Agreement on
the respective dates set opposite their signatures  below, but this Agreement on
behalf of such  party  shall be deemed to have been  dated as of the date  first
above written.

                                     SELLER:

                      CONTINENTAL EXECUTIVE PARKE, L.L.C.,
                      an Illinois limited liability company

                      By:  THE PRENTISS/COPLEY INVESTMENT
                           GROUP, a Delaware joint venture

                           By:  PAC/SIB L.L.C., a Washington limited
                                liability company, Managing General Partner

                                By:  Pacific Realty Associates, L.P.,
                                     a Delaware limited partnership,
                                     Managing Member

                                     By:  PacTrust Realty, Inc.,
                                          a Delaware corporation,
                                          General Partner

Date:     12/16  , 1997                   By:   /s/David W. Ramus
     ------------                               ----------------------
                                          Name: David W Ramus
                                                ---------------------- 
                                          Its:  Vice President
                                                ----------------------



                                    BUYER:

                                    CDW COMPUTER CENTERS, INC.,
                                    an Illinois corporation


Date:            , 1997             By  /s/Michael P. Krasny
     ------------                       ---------------------------
                                        Michael P. Krasny 
                                        ---------------------------
                                        (typed or printed name)

                                        Its:
                                            ------------------------



                                       16