I'm often amazed by the processing speed of my new computer, but I'm disappointed by its inability to tell time. Even with Windows XP's built-in NTP time update service enabled my system's clock is often up to seven minutes fast. To lessen the problem, I now have my system synchronizing its clock every day.

By default, Windows XP's NTP service synchronizes your system's clock every seven days, but the update interval (in seconds) can be changed via this registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
W32Time\TimeProviders\NtpClient\SpecialPollInterval.

Here's a REG file you can run to make your system clock synchronize with your time server daily.