how do I make a user a local admin in a domain?

From: Tim Bergquist (tbergquist_at_okwu.edu)
Date: 06/17/03 

Date: Mon, 16 Jun 2003 18:40:24 -0700

I know this might be a simple answer, but I am vexed.
Most of our users are set as a User and only have user
level privledges to their local computer. We log onto a
Windows 2000 Active Directory.
Some users I want to have administrator level privledges
to their computer.
How do I do this? I have tried several things but can not
find the answer.