You will need to restructure your tables a little, like this:

tblComputer
tblComputerID (identity field, Primary Key)
computername
description

tblUser
tblComputerID (Foreign Key, related to tblComputer/tblComputerID)
username
password

The tblUser/tblComputerID points to which computer is associated with which user.

Then your SQL Statements will have to contain a JOIN on the key

Make sense?

Regards,

Will