There are several options, one of which the first answerer already stated. Another handy one would be the "Print Screen" button, which is common-place on mostly all keyboards. After you press the "Print Screen" button, go to mspaint.exe, by going to:
Start>All Programs>Accessories.Paint
When you open up Paint, press Ctrl+V, to paste it. At that point, you could just reshape and crop as you please. There is a much better option though, in my opinion:
screenshot.exe is a 32.0kb file, that can take an image of any part of your screen, at any ration nonetheless. After taking the picture, you can save it in several formats, such as BPM (Bitmap), GIF, JPG/JPEG, and several others. You will find that you will use it a lot over the years, I know I have. I emailed the executable to you. If you have any problems or questions, dont be afraid to IM me at wiltzandrew1989 on Yahoo! Messenger, wiltzandrew on AIM, or wiltzandrew on MyspaceIM. I am a software collector, and I am likely to have anything you will ever need, software wise.
I hope I helped you out ;)
God Bless!
-Andrew Wiltz