The Magical Jelly Bean Keyfinder is a freeware utility that retrieves your Product Key (cd key) used to install windows from your registry. It also has a community-updated configuration file that retrieves product keys for many other applications. Another feature is the ability to retrieve product keys from unbootable Windows installations.
If you need something more powerful, please compare Magical Jelly Bean Keyfinder with wonderful tool called "Recover Keys". This advanced product key finder is not free, however it doesn't cost much for what it does.
Magic Jelly Bean 126.96.36.199
Product Key finder....if you lose, misplace your key this little jewel will find it for you.