Atomic Time Sync
Works in Windows 9X, ME, 2000 & XP
This program will connect to one of the time servers operated by the National Institute of Standards and Technology (NIST) in the United States, and will compare the time of your computer with the time on the servers operated by the NIST. This program will then display the difference between your system and the servers and if greater than 15 seconds, it will offer you the option of adjusting your PC by the displayed amount.
It can even be set to automatically check the time once a day to keep your PC’s time accurate forever. Best of all, you can download and use this utility at no cost to you!