Magnifier is pretty neat. The first time you use it: in Windows XP, click Start > All programs > Accessories > Accessibility > Magnifier. You can minimize it or dock it. You can set various options. I think Windows key plus down arrow or up arrow to zoom in and out, but I can't verify this... it's Windows key plus + or - to zoom in Windows 7.
http://www.microsoft.com/enable/trai...ierturnon.aspx