Interesting little feature that I have not used that exists in both XP and Vista.
MouseKeys allows you to move the mouse using the numberpad. Its similar to a previously posted program, which was slightly harder to use, but more flexible.
Mousekeys can be accessed this way:

Vista:
Control Panel: Type MouseKeys in search box. Click Move pointer with keypad. Done!

XP: Control Panel: Accessibility Options: Mouse tab: Use Mousekeys. Done!

Thanks Cybernetnews