An Internet Time utility built into Windows XP Home and Professional editions that is supposed to ensure correct system time instead suffers from intermittent bouts of tardiness, PC World has learned. Microsoft intends the utility to synchronize your PC's internal clock via the Internet with the atomic clock maintained by the National Institute of Standards and Technology. The atomic clock is considered the Holy Grail of timekeeping. It is referenced daily by millions, from the military to stock market traders and researchers, by means other than Microsoft's Internet Time utility. Read More for more details.
Check out the article @ PC World