limit selected user to log on to particular workstation

I have win2003 server Machine
and 20 hosts(winXP) connected to the server
I need to make a workstation to be logged in by only particular user

For Example
let there be 20 users in active directory say u1,u2,u3.

I need only user u1 to log in to pc1 and not other users.

Is there any way
Please help me