The Ophcrack Windows password cracker is by far the best free Windows password recovery tool available. It's fast and easy enough for a first time Windows password cracker with a basic knowledge of Windows.
With Ophcrack, you don't need any access to Windows to be able to recover your lost passwords. Simply visit the site, download the freeISO image, burn it to a CD and boot from the CD. The Ophcrack program starts, locates the Windows user accounts, and proceeds to recover (crack) the passwords - all automatically.
In a test on a Windows 7 PC, Ophcrack recovered the 10-character password to my administrator account in 40 seconds. Ophcrack supports Windows 7, Windows Vista, and Windows XP.