Group Policy to add users to local admin group

I work in a win 2003 server environment with XP workstations and I would like to grant all users local admin rights to their PC’s. Is there a Group Policy that automates this. If possible I want to limit admin access to the specific user instead of granting all users local admin rights to all workstations. I just want “user A” to have local admin rights to his particular PC.

Any help would be great

Thanks