The following was tested on a Windows 2003 R2 with SP2, but it should work on every system with w32time installed.

Open up a command prompt (start, run, cmd.exe, you know).

Then punch in these lines:

net time \\your-server-name /setsntp:some-ip-or-pool.ntp.orgnet stop w32timenet start w32time

The way NTP works, the sync does not occur immediately, but it should be visible within a few minutes after w32time has started again.

Notice
If it doesn't work for you, check whether your time zone is correct, and whether the time of your server and the real time differs with over 3600 seconds. Ntpd would not sync if the difference was over an hour.

To query the current NTP servers  ...