The free, open source Ophcrack Live CD is a Windows account password cracking tool designed to help you recover lost Windows passwords.

After you download the 462mb .iso and burn it to a CD, just restart your computer and boot up the Live CD. Once the CD boots, Ophcrack automatically loads and is on its way to cracking your password. So how well does it work?

Honestly... Ophcrack is creepy. It cracked my (somewhat mediocre) 13-character alphanumeric password in about 5 minutes. Like most powerful tools, Ophcrack can be used for the forces of both good and evil, but for anyone who's been locked out of their Windows user account because you can't remember your password, Ophcrack can be very good. It may also encourage you to beef up the security of your user account password - that's what it did for me. Thanks K-milo! — Adam Pash