By using the net time command on each users pc,(possibly including the bdc!) redirecting to the pdc.
eg.
c:>NET TIME \\Server /set /y
It is a good idea to do this in the logon script.
marcdmac has a good looking script written in vb in this very forum...
of course, you will need to delete the ' on the respective line...
see...
thread96-749465