Windows password recovery tool

If you need to recover the passwords from a Windows XP or Windows Vista Machine, the easiest thing to do to retrieve your password is to use OPHCrack live CD.

I inherited a Dell Precision 340 the other day with Windows XP on it. It had been sitting in a PC graveyard for some time before being shipped to me.
This is how I was able to recover the administrator password to get this machine setup.

Download OPHCrack from sourceforge.
Windows XP:
http://downloads.sourceforge.net/ophcrack/ophcrack-xp-livecd-2.1.0.iso

Windows Vista:
http://downloads.sourceforge.net/ophcrack/ophcrack-vista-livecd-2.1.0.iso

Burn the .iso to a CD using a tool like InfraRecorder

Place the OPHCrack Live CD into the CD drive on the unusable machine and then turn it on.

If the unusable machine is configured to boot from CD first then OPHCrack will bootup before Windows. If not, then you'll have to do what I did.
When the system is booting, navigate into the boot loader options menu. If you don't know which key to press and it doesn't tell you upon booting up. You can just casually lean on the row of F{1-12} keys and that usually that works :-)

OPHCrack got right to work after it loaded and it determined all of the user's passwords within the time it took for me to grab another cup of coffee.

Hope that helps.
Here's another tutorial here.
and here.