Have you ever run across something on screen that you couldn't copy- such as error messages. If so you should try CaptureWiz. It's a small program than when you click on the icon, throws up a viewfinder that you can resize to fit your needs and will capture whatever portion of the screen you'd like.
There is a 30 day free trial and the program itself is inexpensive.
CaptureWiz is only $19.95 and CaptureWizPro only $29.95. Check it out at http://www.pixelmetrics.com/CapWizPro/CapWizPro.htm
(Hmmm.... Wonder if the company will let me upgrade for free with this plug? LOL