If you hate balloon tips (those irritating reminders that pop up from the Windows XP taskbar) and want to stop them from happening, do this*...

1. Start > Run > Regedit

2. Find the following key:
HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Advanced

3. Right-Click on the 'Advanced' key and do 'New > DWORD VALUE'

4. Give this the name 'EnableBalloonTips'

5. Give this key the value '0'

* Disclaimer: Registry editing is potentially dangerous - if you make a mistake you could royally shaft your PC. If you're not confident editing your registry, don't do it!