The Snipping Tool is a program that is part of the Vista Tablet PC Optional Components feature. Once you will get your hands on this snipping tool, you will realize that taking screenshots is just a fun in Vista.
Snipping Tool allows you to capture portions of your screen using four methods and then save these snips as a JPG, GIF, PNG, or MHT file. The capturing methods in which you can take the snips are free-form, rectangular, window, and full-screen.
With free-form mode you can select any portion of the screen with the help of the scissor appearing on the screen.This scissor appears when you select a free-form snip. The The Rectangular snip mode will allow you to quickly draw a rectangle on the screen and capture everything inside it. In the Window snip mode you just have to select a window with the mouse and the Snipping Tool will take a screenshot of it, and as the name suggests in Full screen mode you can capture screenshot of whole screen.
To find it, go to Start -> All Programs -> Accessories -> Snipping Tool.