thanks for the reply DoG.
guess what:
this is what in the Help and Support Center in Windows Server 2003 Enterprise Edition!
To protect your files by using a screen saver password
Open Display in Control Panel.
On the Screen Saver tab under Screen saver, click a screen saver.
Select the On resume, password protect check box.
If Fast User Switching is turned on, select the On resume, display Welcome screen check box.
if we could enable fast user switching, somehow?