Originally Posted by
elCheapoDeluxe
I think that the time synchronization doesn't work if the computer is part of a domain / active directory. It will synchronize the time with your domain controller instead.
Originally Posted by
LIH Prem
XP Pro has a built-in ntp client. You don't need any special client software.
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Also, if you are part of a domain, you want to use the domain's time server, and not an external one.
If your computer is in a domain it is pretty important to let the Windows Time Service (the built-in NTP client) just sync to your domain. In other words don't mess with it. If the time gets out of sync by more than 5 minutes (I'm 99% sure this is the margin) then authentication will start failing due to the way Kerberos (the authentication mechanism) is built. If you're in a domain but never on your corporate network (VPN or for real) your computer will likely start to drift and eventually have other issues, including the computer account expiring on the domain, but that takes several months of being disconnected before it is really an issue.
If you are not in a domain the computer will try to sync to time.microsoft.com by default. You can change that with the command "net time /setsntp:<servername1,servername2,...>" or using the local security policy GUI described above. The MS one should be fine in most cases.