I use Jing a lot http://www.techsmith.com/jing.html
it is free and really a nice piece of screen capture software from Techsmith. If you have Windows 7 there is a build snip program.
We have a Help Center article that may help.
I use JING and SnagIt......I'm migrating more and more to SnagIt...it has a little more functionality
Thank you Kos
Snagit definitely has more functionality but for "free", Jing works. Both solid and dependable.