I have configured a NTP time server on our domain controller per instructions from Microsoft's support site. I made all those registry entries. Now I am trying to find out how to insure our client PC's will poll that server at regular intervals to keep their time current. I have been ready so much about this that my head is swimming and just need to know.
w32tm /config /syncfromflags:domhier /update
Also you can set up the time server in Group Policy: Computer Configuration > Policies > Administrative Templates > System > Windows Time Service > Time Providers > Enable the Configure Windows NTP Client policy and set your DC as the NTP Server.