If you are doing presentations for other people, recording your own screen, or just have a bit bad eyesight, this little tip may suit you well.
Windows 7 has a built in program called Magnifier.
This program allows you to zoom in on a specific part of the screen.
To open the Magnifier tool, just hold your Windows key, and press +
Theres also a couple of different viewmodes and options easily available from the menu.