after getting the user variables do this
date("d/m/Y h:ia",time()+(3600*$user['timezone']);
Ill explain how it works very easy though
Basically will out put 11/11/2003 12:50pm as an example
3600 is how many seconds in the hour so than that is being timed by the timezone which must have a - or + not so much the + in front of the timezone.
Hope that helps