I was recently asked how to capture windows screens for making tutorials. There are inexpensive screen capture tools available. If you just want a screen shot to put in a word or excel document then pressing < alt + ptrnsc > and then opening windows paint and selecting edit and then paste from the menu will do the job.
Just as inexpensive, and it allows you to capture a video is Windows Media Encoder. This is a free download from Microsoft if you have not already got it.You can get the latest version for Xp at:
http://www.microsoft.com/windows/windowsmedia/player/11/default.aspx
You can get the latest version for Vista at:
http://www.microsoft.com/windows/products/winfamily/mediaplayer/default.mspx
Guidelines on getting the best results are at:
http://www.microsoft.com/windows/windowsmedia/howto/articles/ScreenCodec.aspx
and a getting started guide is it:
http://www.microsoft.com/windows/windowsmedia/howto/articles/screencap.aspx
If you find the Microsoft way to do this a little complex, how about having a look at the following free application:
The Jing Project
Also, if you would like a more feature rich tool,TechSmith who developed The Jing Project also have a commercial offering calledCamtasia, it looks pretty good.