We have some Windows 2000 servers we administer that are authenticating against some NT domain controllers. You can set up your Windows 2000 servers to synchronize time with an outside source:

C:\>net time /querysntp
This computer is not currently configured to use a specific SNTP server.
The command completed successfully. 

For a list of NTP servers, see this page. Let’s configure it for clock.isc.org:

C:\>net time /setsntp:clock.isc.org
The command completed successfully.

Verify that it stuck:

C:\>net time /querysntp
The current SNTP value is: clock.isc.org 
The command completed successfully.

You may need to bounce w32time to see your results:

C:\>net stop w32time
The Windows Time service is stopping.
The Windows Time service was stopped successfully.
C:\>net start w32time
The Windows Time service is starting.
The Windows Time service was started successfully.

Note that you only want to do this on machines that are not already synchronizing with the domain controller, which happens automatically with active directory. This is also the method you would use to select an outside source to synchronize time with on the PDC of the domain at the root of the forest.