Balloon Tips is a new & unique feature in Windows XP. They are used to catch the users attention about all possibly imaginable things happening in Windows XP. If you are annoyed by them like some of us are then you can disable the Balloon Tips via the registry. Go to: HKEY_CURRENT_USER Software Microsoft Windows CurrentVersion Explorer Advanced
Look for "EnableBalloonTips" and change the the DWORD of 1 to 0. Done.