<PAGE>   1
                                                                      EXHIBIT jj

[INFORMATION RESOURCES INC. LETTERHEAD]


                                   September 23, 1997

Mr. James R. Chambers
425 Cherry Lane
Mendham, NJ 07945

Dear Jim:

         We are delighted that you have accepted our offer of employment. The
purpose of this letter is to summarize our understanding of the terms to which
we have agreed.

         You will be employed as Group President responsible for IRI's U.S.
Commercial Businesses which include Customer Sales and Service, Product
Management, Solution Centers, Retail, and Marketing. Your base salary will be
$315,000 per year, and will be reviewed on May 1, 1998, and annually thereafter.
You will receive merit consideration based on your performance, and any increase
will be pro-rata based on your start date. Your initial annual bonus target will
be 40% of your base salary, and your final bonus will be based on your
performance, and IRI's bonus plan formula. For 1998, we will guarantee you a
minimum bonus of $80,000, payable on or about March 15, 1999. We will also
provide you with a $40,000 sign on bonus payable 15 days after your start date.
You will be required to repay the sign on bonus to IRI if you are terminated for
cause or you voluntarily resign your position before your one-year anniversary.

         You will enjoy all employee benefits and perquisites available
generally to the other senior executive officers of the Company. This includes
IRI's flexible benefits program which consists of health and welfare plans, life
insurance, disability, 401(k) plan, holidays, personal leave, sick leave and
vacation allowance (four weeks vacation per year).

         On you start date, the Company will grant you 125,000 options under its
Executive Stock Option Plan, to be evidenced by the Company's customary form of
stock option agreement. For these 125,000 options, one-third will vest on each
of the first three anniversaries of the starting date of your employment.

         Should a "change of control" (defined as the sale of the Company,
whether by merger or otherwise, or the acquisition of more than 25% of the
company's common stock by an acquirer, or group acting in concert) occur during
your employment, the following will apply: If a change in control occurs before
the second anniversary of your employment and you leave the Company within one
year thereafter for any reason (other than for cause), your options (including
any granted to you in the future) will continue to vest and become exercisable
(until 30 days after the last options vest) in accordance with their vesting
schedules notwithstanding the termination of your employment. If a change in
control occurs after the second anniversary of your employment, all your
unvested options will immediately vest and become exercisable.

         Upon starting with the Company, you will be expected to execute a
customary noncompetition and confidentiality agreement (attached). Should your
employment be terminated (including a reduction in responsibility or
compensation) for any reason other than for cause, death or your voluntary
resignation (except in case of resignation within one year following a change in
control), you will continue for the next twelve months to receive all benefits
including compensation at a rate equal to 140% of your base salary then in
effect. Again, if your employment terminates for cause, or as the result of your
death, or your voluntary resignation (except for change of control as stated
above) you will receive no severance benefits. Also, any options that would
otherwise vest in the succeeding 18 month period following such termination not
otherwise vested pursuant to the above change in control provision will vest
immediately.



<PAGE>   2


JAMES R. CHAMBERS
PAGE 2



         You will also receive initially IRI's full relocation package for
executive officers. As we have discussed, you will work out of IRI's Fairfield,
NJ office, but will be expected to work in Chicago an average two days per week.
Our intent is to have you move to Chicago, one year from your start date, but I
will evaluate with you how things are working on or about July 1, 1998,
regarding this issue. Please contact Gary Newman regarding any aspects of your
employment offer, especially IRI's benefits and relocation policies.

         Jim, everyone is extremely excited about your joining our team. We know
you can make a difference for IRI, and believe we can offer your the challenges
and career opportunities you desire. On behalf of the Company, the Board of
Directors and our entire senior management team, we express our great pleasure
at your forthcoming arrival and look forward to a long term and mutually
rewarding professional relationship with you. Welcome aboard!

                                             Sincerely,




                                             Gian M. Fulgoni
                                             Chief Executive Officer


Accepted this 3rd day of October 1997



--------------------------------
         James R. Chambers




cc:  Gary Newman


<PAGE>   3


[INFORMATION RESOURCES INC. LETTERHEAD]

August 31, 1998


Mr. James R. Chambers
425 Cherry Lane
Mendham, NJ 07945

Dear Jim:

         This letter will confirm our oral and electronic mail communications
regarding amending your September 23, 1997 employment letter and the terms of
new stock options recently approved by the IRI Compensation Committee. The
option vesting and exercise rights described in this letter are in addition to
those described in your offer letter of September 23, 1997.

         The 125,000 options currently held by you will vest and be exercisable
according to the terms set forth below, in the event that your employment is
terminated by IRI without cause or is terminated by you for "Good Reason".

         For purposes of this letter, you shall have ""Good Reason" to terminate
your employment hereunder if, but only if:

(a)      without your express written consent, you are assigned any duties
         inconsistent with your position, duties, responsibilities and status
         immediately prior to a change in your reporting responsibilities, title
         or offices, except (i) in connection with your reassignment by the
         senior management of Information Resources to a comparable position
         (i.e., same salary and grade level), (b) the commencement or
         continuation of a disability preventing you from performing your duties
         and responsibilities; or (c) you are removed from or not re-elected to
         any of your offices or positions except in connection with such
         reassignment or the commencement or continuation of a disability
         period;

(b)      a reduction is made by Information Resources in your base salary,
         except as and only to the extent that the Compensation Committee of the
         Board of Directors (or its successor) decreases the base salary of all
         senior officers who are at the rank then held by you in the same
         fashion.

(c)      Information Resources fails to continue in effect any benefit, bonus or
         compensation plan, stock ownership plan, stock purchase plan, stock
         option plan, life insurance plan, health-and-accident plan or
         disability plan (other than those plans which expire by their express
         terms) in which you are participating, other than as part of a
         reduction or change generally applicable to other senior officers of
         Information Resources; or

(d)      Information Resources fails to obtain from any successor entity to
         Information Resources an agreement to perform this Agreement to the
         extent and in the manner required to be performed by Information
         Resources.

         If any such termination by IRI without cause or by you for "Good
Reason" occurs before the second anniversary of your employment, your options
will continue to vest and become exercisable (other than terminated or expired
options until 30 days after the last options vest) in accordance with their
vesting schedules notwithstanding the termination of your employment. If any
such termination occurs after the second anniversary of your employment, all
your unvested options will immediately vest and all your options (other than
terminated or expired options) shall be exercisable for a period of 24 months
from the date of termination of employment.



<PAGE>   4


Jim Chambers
August 31, 1998
Page 2



         Further, if Gian Fulgoni ceases to be the Chief Executive Officer of
IRI or Tom Wilson ceases to be Chairman, such change shall be treated as if it
were a "change of control" for purposes of accelerated option vesting and
exercise periods, as described in IRI's offer letter to you of September 23,
1997.

         You have also been granted another 125,000 stock options with a grant
price of $10.938 as of August 25, 1998. You will become vested in these options
after one year from the grant date. These options will have all of the
conditions as the original options granted to you and stated above. This
includes a two year time period to exercise your options when a change of
control, good reason or any type of termination (except cause) occurs.

Very truly yours,



Gary S. Newman
Executive Vice President
Human Resources
                                            Accepted:


                                            ------------------------------------
                                                     James R. Chambers



cc:      Gian Fulgoni