I'm not sure what you want exactly, since there obviously is only one
single "correct" time, with different offsets for different time
zones.
A normal user should not have permission to change the time on the
server, but if you are running Windows 2003 TS, you can automatically
adjust the time for each session, according to the time zone the
client is in.
Configuring Terminal Server for Differing Time Zones
http://www.microsoft.com/technet/treeview/default.asp?
url=/technet/prodtechnol/windowsserver2003/proddocs/deployguide/sdcce
_term_zisr.asp
If you run W2K TS, you will need a 3th party application for this,
e.g. TimeMachine from
http://www.solution-soft.com/timemachine.shtml
