Login failed for user COMPUTER\ASPNET

These are my settings:

winXP
SQL 2000 EVAL, server settings - Use the local system account
mixed mode
iis5.1

I recently got a new computer with winXP and I am trying to move everything from my old win2000 system.
I copied the database over to the newly installed server and I can see the tables with the Enterprise Manager. I just can not access them through my application.

When installing SQL server, I had to use the local system account. It would not accept a password for a Domain User Account. does this matter?
I did a "grant access" to the database for COMPUTER\ASPNET but that did not help.

Thanks in advance

below is my error
Computer name is GREG

Server Error in '/' Application.
------------------------
Cannot open database requested in login 'breeds'. Login fails. Login failed for user 'GREG\ASPNET'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Data.SqlClient.SqlException: Cannot open database requested in login 'breeds'. Login fails. Login failed for user 'GREG\ASPNET'.
Source Error:
Line 58:
Line 59: DS = new DataSet()
Line 60: MyCommand.Fill(DS, "bds")
Line 61:
Line 62: breedslist.DataSource = DS.Tables("bds").DefaultView

Got it!
Thanks to another post, anyway, BDESMOND wrote:

"The issue is that ASP.Net is running under the ASPNet account. SQL Server does not have a login for the ASPNet user. If you have Enterprise Manager, go in there, add a login for ASPNet in the Security section, and then grant rights to this user in the Users Section of your database.

If you don't have enterprise manager, postback, and I'll find you the post I made with commandline instructions."

Thank You, Brian!
Greg
Hi
I've running into the same type of problems. I've created a new DB and got the 21008 error..login failed for Computer\..." Then I tried to add the Computer\ASPNET user to the DB via the SQL Enterprise Mgr but got an "user already exists" error. (ASPNET is a user in all the examples I've downloaded). I think I've corrected that issue with a command line instruction ...and now I get "login failed for Computer\Administrator".

Foregive me if this is a rediculous questions, but do you know why the program is looking for Computer\Administrator instead of Computer\ASPNET?

Thanks