I suggest the Meinberg Time Client, available for free on the Web. This client is a full implementation of the NTP protocol, rather than the stripped-down version (called “SNTP”, where S = ”simple”) used by D4. Both the built-in Windows time client and D4 can be off by as much as a second. Meinberg, after an initial period of a few days where it is invisibly self-adjusting to your computer environment, will keep your computers accurate to around ±10 ms – yes, that 10 milliseconds. :-) At that point, having verified the final correction factor, you can forget about it.
Google for it and you will find it. Another hit that might come up in your Google attack is a document that a guy wrote a while back about how to set up and use the Meinberg client, how to make it a Windows Service, etc. Very will written with lots of screen shots. Maybe somebody on the list will have a copy of this PDF handy that they can send to you. The instructions included with the Meinberg NTP client are rather sparing, and assume the users are basically familiar with how NTP works and how Windows Services work, etc. BTW, Meinberg will turn off the Windows time client for you, if it is on. You shouldn’t have to do anything. One other thing: I think it supports Windows XP, but I wouldn’t bet the ranch on it. Make sure it does before installing it.
Unlike D4, which is technically an obsolete product, no longer being supported by its (defunct?) developer, the Meinberg time client is kept up to date and is fully supported by Meinberg.
If I were you, I would upgrade to Windows 7, unless you have hardware components that aren’t supported by it. Or maybe you’re just waiting for Windows 8. Just as a heads-up, Windows 8 is right around the corner. A full Beta version is now available for download, and the apps that have been written for it so far are all free during this Beta period. When launched, many of the apps will no longer be free.
Finally, Microsoft is saying that Windows 8 represents a major paradigm shift for Windows, as drastic as the shift from Windows 3.1 to Windows 95 was. Be prepared to learn! LOL :-)
This information was derived from cNet, BTW.