Disable Default Notifications

Windows XP can be very insistent about you checking for auto updates, registering a Passport, using Windows Messenger and so on. After a while, the nagging goes away, but if you feel you might go insane before that point, run Regedit, go to HKEY_CURRENT_USER/Software/Microsoft/Windows/Current Version/Explorer/Advanced and create a DWORD value called EnableBalloonTips with a value of 0.