Zoom+ by GipsySoft is good software. Simple clean Windows screen zoomer. Very useful for looking at per-pixel positioning, sampling colours from a page, measuring the size of icons, and generally seeing the detail of things on screen. Flawlessly executed, simple and intuitive interface. Even supports fun digital video feedback tricks.
GipsySoft also makes Winspector, a handy replacement for Spy++ for digging into how Windows apps work.