Windows 2000 has an integrated time synchronisation service, installed by default, that can synchronise to a NTP Time Server. Indeed, by manipulating registry settings for the service it can act as both an SNTP client and server to synchronise other network clients.
The 'windows time' service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for w32time can be found in the registry at:
Windows 2000 can operate as an NTP client and synchronise to an NTP server by setting parameter 'ntpserver' to the IP address of a NTP time server.
By default, the Windows 2000 machine will synchronise to the specified NTP server every 8 hours (or 3 times a day), which may not be enough to maintain accurate synchronisation. This period can be reduced by setting the 'period' parameter to how many time a day synchronisation is required. Setting the period to 48 will activate synchronisation with the NTP server once every half hour.
Windows 2000 can also be configured to act as an NTP server by setting the 'localntp' parameter to '1'.
After editing any of the registry entries for the windows time service, the service must be restarted for the settings to take effect.
The services can be started or stopped from the service control applet in 'administrative tools'. Alternatively the service can be controlled via the DOS net command thus:
net start w32time
net stop w32time
More information on the Windows Time service can be found at http://support.microsoft.com/kb/q223184/