Magical Jelly Bean Software - Magical Jelly Bean Keyfinder v1.41:
"The Magical Jelly Bean Keyfinder is a freeware utility that retrieves your Product Key (cd key) used to install windows from your registry. It has the options to copy the key to clipboard, save it to a text file, or print it for safekeeping. It works on Windows 95, 98, ME, NT4, 2000, XP, Server 2003, Office 97, and Office XP. This version is a quick update to make it work with Windows Server 2003."

http://www.magicaljellybean.com/keyfinder.shtml