Allow users to user their own usb key

[Jac]

Hi we are running windows xp sp2 with windows 2003 sp1

I want to allow certain users to use their own usb key even if they are
non-admin

I tried the GPO "Load and unload device drivers" and ive put the group
"Domain Users" on it. I tested that on a pc but it ask me the username and
password of an admin users

Any help please

Thanks

JAc