<PAGE>   1
                                                                   EXHIBIT 10.28

                            AVENIR(TM) PROPOSAL FOR
                                     HS.COM

G. SYSTEM / DATA LICENSE AGREEMENT

This is a Data License Agreement (Agreement) effective 9/30/98 (Effective Date)
between Healthdemographics, Inc. (a Delaware Corporation) (HD) with principal
offices at 4901 Morena Blvd., Suite 701, San Diego, CA 92117 and HS.com
(Company) with principal offices at 380 Vista Abierta, El Cajon, CA 92019.

Definitions:

a.    "AVENIR and HealthPacs" Data are HD proprietary products that include
      demographic data, population based models of the incidence of diseases by
      category, estimates of the demand for services (inpatient, outpatient,
      physician services, etc.). These models present estimates of the current
      demand and forecasts of the changes in demand that can be anticipated over
      the next five (5) years, as described in Health-demographics most recent
      documentation.

b.    For purposes of this Agreement, "Product" or "Products" shall be defined
      as (a) each Product designated in this Agreement, including but not
      limited to AVENIR and HealthPacs; and (b) any materials, know-how and
      technical information provided to Company in written form for use in
      connection with each Product.

Grant of License:

a.    AVENIR/HealthPacs; Subject to the terms and conditions of this Agreement,
      HD hereby grants to Company, a non-exclusive, non transferable license to
      use certain AVENIR/ HealthPacs databases specified in Exhibit A, attached
      hereto and incorporated herein, to create specialized reports to be sold
      in conjunction with Company's services to Company's customers. Company
      shall not resell in whole or in part the HealthPac databases. All other
      uses of the Product are strictly prohibited under the terms of this
      agreement.

b.    Company may not authorize third parties to use or market the Product, or
      any part thereof.

c.    All reports, maps and databases generated by the AVENIR System that
      contain Healthdemographics content shall reference Healthdemographics as
      the source of the data.
<PAGE>   2
                            AVENIR(TM) PROPOSAL FOR
                                     HS.COM

Access to the Product:

a.    Delivery: Upon execution of this Agreement, HD will deliver the Product to
      the Company in the format outlined in Exhibit A.

b.    Product Changes: HD reserves the right to make any changes, modifications
      or enhancements to the Product during the term of the Agreement as long as
      they do not diminish the quality of or substantially alter the content of
      said Product.

Term of License: The term of license granted hereunder shall commence upon the
Effective Date specified herein and continue for one (1) year.

Payment: Company agrees to pay HD an annual license fee for the AVENIR/HealthPac
data of $120,000. The first payment of $40,000 will be due Net 60 from product
delivery. The second payment of $40,000 will be due Net 150, and the third
payment of $40,000 will be due Net 180. Company is responsible for all
applicable use and sales taxes.

HD Support:

a.    HD agrees that during the term of this Agreement, HD will furnish all
      modifications, enhancements and corrections to the Product necessary to
      fulfill its obligations to Company under the Agreement.

b.    Company shall be entitled during the term of this Agreement to the
      following products and services from HD at no additional charge: (1) one
      copy of each appropriate user manual, (2) use of all Product
      modifications, improvements, and updates, and (3) toll free telephone
      support Monday through Friday, 8:00 a.m. to 5:00 p.m. Pacific Time,
      excluding legal holidays, for all authorized personnel within Company's
      organization.

Copying the Product: Other than a single copy for backup and archival purposes,
Company shall make no copies of the Product or any part thereof without the
express written consent of HD.

Limitation of Liability: HD shall not be responsible for any statement or
representation made in regard to the Product by an employee of Company.
<PAGE>   3
                            AVENIR(TM) PROPOSAL FOR
                                     HS.COM

OTHER THAN AS SPECIFICALLY SET FORTH IN THIS AGREEMENT, HD MAKES NO
REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, AS TO THE MERCHANTABILITY,
FITNESS FOR ANY PARTICULAR PURPOSE OR OTHERWISE WITH RESPECT TO THE PRODUCT, NOR
SHALL BE LIABLE FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF HD
HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. In no event
shall HD's liability to Company, under this Agreement, if any exceed the amount
of payments made by Company to HD under this Agreement.

Ownership of Product: The Product shall at all times be and remain the sole and
exclusive property of HD. It is mutually agreed that this Agreement involves a
license for the use of the Product and that nothing contained herein shall be
deemed to convey any title or ownership in the Product to Company.

Termination: Either party may terminate this Agreement if (a) the other party
commits a breach of the Agreement, and (b) said breach has not been cured to the
reasonable satisfaction of the non-breaching party within thirty (30) days of
receipt of written notice from the non-breaching party stating the nature of
said breach, and delivered by registered or certified mail.

Indemnification by HD: HD represents and warrants that it has title or
proprietary rights to license the Product, and/or to sublicense any aspect of
the Product to which HD does not have title or proprietary rights. HD shall
defend, indemnify and hold Company harmless from any claim that any part of the
Product infringes an any third party, provided that HD is notified within 90
days by Company of such claim. HD shall have sole control of the defense with
respect to the claim (including settlement of such claim) unless HD agrees
otherwise.

Indemnification by Company: Company shall defend, indemnify and hold HD harmless
from and against any losses, damages, claims, demands, suits and liabilities
(including reasonable attorney's fees) that may directly or indirectly result
from Company's use of the Product.

Survival of Obligations: HD and Company's obligations under this Agreement which
by their nature would continue beyond the termination, cancellation or
expiration of this Agreement, including by way of illustration only and not
limitation, those in clause "Limitation of Liability" shall survive
termination, cancellation or expiration of this Agreement.
<PAGE>   4
                            AVENIR(TM) PROPOSAL FOR
                                     HS.COM

Notices: Any notice to be given under the Agreement shall be given in writing
delivered to the address of each party set forth, or to such other address as
either party may designate by written notice to the other.

Assignments: This Agreement may not be assigned by either party in whole or in
part, except to subsidiaries or affiliates, without prior written consent of the
other party. Any attempted assignment absent such consent shall be void.

General Provisions: Should any provision of this Agreement be held by a tribunal
of competent jurisdiction to be contrary to law, the remaining provisions shall
remain in full force and effect. This Agreement constitutes the entire
understanding between HD and Company and may not be altered except by a written
contract signed by authorized representatives of HD and Company. The terms and
conditions of this Agreement are offered and valid until September 30, 1998.
Please sign and return two copies of this agreement. This provides original,
signed copies to HS.com and Healthdemographics.

Accepted and Agreed:

Healthdemographics                       HS.com
4901 Morena Blvd.                        380 Vista Abierta
Suite 701                                El Cajon, CA  92019
San Diego, CA  92117

/s/ M.D. Chermak                         /s/ C.R. Smith
----------------------------             --------------------------------------
Michael D. Chermak                       Charles Smith, President
Chief Operating Officer                  Printed Name/Title

Date:  9/29/98                           Date:  9/29/98
<PAGE>   5
                            AVENIR(TM) PROPOSAL FOR
                                     HS.COM


                                    EXHIBIT A

                                PRODUCT LICENSES

A. AVENIR/HealthPac Database License

      The following HealthPacs are included for the entire United States, by Zip
Code, County, and State:

                              HealthPac Databases:

<TABLE>
<S>                          <C>   <C>   <C>
 1.   Ambulatory             [X]    9.   Managed Care (county level only)    [X]
 2.   Behavioral Medicine    [ ]   10.   Pediatrics                          [ ]
 3.   Cancer                 [ ]   11.   Provider Inventory                  [X]
 4.   Cardiovascular         [ ]   12.   Rehabilitation                      [ ]
 5.   Demographic            [X]   13.   Renal Care                          [X]
 6.   DRG                    [X]   14.   Respiratory                         [ ]
 7.   Eyecare                [ ]   15.   Senior                              [X]
 8.   Hispanic               [ ]   16.   Women's Care                        [X]
</TABLE>

Additional Data Included

Hospital MedPar and Nursing Home Cost Database

Mailing list databases for: Hospitals, Diagnostic Imaging Centers, Kidney
Dialysis Centers, Nursing Homes, Ambulatory Care Centers, Outpatient Surgery
Centers, and Medical Device, Supply, and Equipment Manufactures and
Distributors. These mailing lists will be geocoded, and will contain contact
names and phone numbers.

B. License Title and Product Return: HD shall retain all rights and title to the
licensed Products described herein. Upon expiration of this Agreement, Company
shall return to HD all licensed Products within five (5) business days.

Use and Transferability: The AVENIR/HealthPac Product database access is
licensed for twelve concurrent users. Company may physically transfer the
Product from one computer to another provided the Product is used on only twelve
computers at a time. Company may not distribute copies of the Avenir software
application to others.
<PAGE>   6
                            AVENIR(TM) PROPOSAL FOR
                                     HS.COM


                                   ADDENDUM TO
                          SYSTEM/DATA LICENSE AGREEMENT

This Addendum is attached to and made a part thereof of the System/Data License
Agreement (Agreement) between Healthdemographics (HD) and HS.com, Inc. (Company)
executed on September 29,1998 (date). This Addendum shall have the same binding
force and effect on all parties hereto as does the Agreement, and shall take
precedence over any and all conflicting or contrary language contained in the
Agreement or prior Addenda. HD and Company agree as follows:

In consideration of payment to Healthdemographics of the additional sum of
$250,000.00, Healthdemographics covenants and agrees that during the initial
term-year of this Agreement it shall not license (the product) to any other
party for use in the business of Internet-based sales or purchases of medical
supplies, devices or equipment; provided, however, that this covenant shall not
apply to other pre-existing current licensees of (the product) from
Healthdemographics whose license agreements do not contain such a restriction on
usage.

Payment is due Net 90 from the execution of this Addendum.

Agreed and Accepted.

Healthdemographics                       HS.com
4901 Morena Blvd.                        380 Vista Abierta
Suite 701                                El Cajon, CA  92019
San Diego, CA  92117

/s/ Michael Chermak                      /s/ Ben Carter, CFO
-------------------------------          ---------------------------------------
Michael D. Chermak, COO                  Signature & Title

Date: 12/24/98                           Date: 12/24/98