How do you set the time in your house? I don't mean do you know how to set the clock on your VCR, but what TIME do you actually enter? Do you just use the normal 'best guess' approach that practically everyone else does? If so, then get ready for the real deal - set your clock using THE timekeeping source, the National Institute of Standards and Technology. NIST maintains the primary frequency (time) standard for the United States, and operates a special server using the Network Time Protocol (NTP) to allow Internet users to get the time from them! Of course, if you're not based in the US, don't worry, you can go to the NTP Homepage and get a listing of servers worldwide, so you can pick the one closest to you.
Once ATS is set up, you can have it periodically set your system clock; plus it even has a built-in NTP server so you can synchronize all of your other computers quickly and easily! You can even specify a custom time offset to ensure that it sets your clock just the way you like it (I like my clocks 10 minutes fast, so I'm always a bit early).
Although this small program has not updated since December, 2001. It can run smoothly on Windows XP/2003. Without "run as service" feature, you should place the shortcut to "Startup" folder for autorun when login or make a schedule task.
Within any local network you can config one computer acts as time server, retrieve correct time from outside. Others simply installed as client and sync time from the local time server.
more info: How to configure an authoritative time server in Windows Server 2003
