Windows Vista has a great tool to make screenshots very easily, but this tool is somewhat counter-intuitively called the “Snipping tool” for reasons you’ll understand in a minute. Using this tool, you can easily make screenshots of your screen or just a small selection of it. This tool can be found at:
Start > Programs > Accessories > Snipping Tool
Using this tool you can make screenshots in several ways, for example you can make a free-form snip, rectangular snip, window snip, or full screen snip. Once you start using it, you’ll find it to be a valuable tool!