Change the "screen saver" with a Profile: How??
 

With Windows 2000 or Windows XP the screen saver should be unique to each
user-profile. If you are using Windows 98 or (heaven forbid) Windows Me
then I believe it's one screen saver for all.

Actually, I think even the 9x series of Windows allows each user to have
his own screen saver...that is if user profiles are enabled.