Screenshot software

Here's a free one for Mac that looks pretty user friendly:
http://www.yellowmug.com/snapndrag/

Instructions for using Print Screen button with Windows XP, Vista and Windows 7:

1. Maximize the window you'd like to capture.
2. To copy/capture the current window, hold down ALT + Print Scrn at the same time. To capture the entire screen, just press Print Scrn.
3. Open a new document in MS Word.
4. Paste the screen shot by holding down CTRL and V at the same time.