I second it. It's free and portable. I 've been using this for last three years both under XP and Vista. Since it is portable you can try it and discard if you don't like. No installation and uninstallation, cleaning the registry blah..blah. Light footprint.
FastStone Capture is far by the best Screen Capturing software i've came across.
Why its good...
1. Screen Clipping w/Built in Editor.
2. Video Recording
3. Very light on system resources and responsive.
Freeware 2nd option PicPick
All the features of the faststone capture except screen recording and its very light on system resources and powerpacked with features.