Local Administrator Rights

Under win2003 how do I setup a user in a domain to have administrative access to there local machine.

For example:

#1) The users in the domain can login and access the things on the network server they need to but can’t do simple things like change there screen saver settings.

#2) They can’t install local software like peachtree on there local machine?

Is there a LOCAL ADMIN right somewhere I’m not setting correctly?