Bit of a roundabout way of doing it, but download a utility called KonBoot. Boot from the burned disk (the CD, NOT the hard drive!) and let Windows load. At the password prompt, enter any password (you can even leave it blank). Once the desktop has loaded, enter the user accounts panel and create a new, dummy administrator account (again, calling it whatever you want) and log out. Log into the dummy admin account you just created and then go back to the user accounts panel. Change the password for the account you were trying to get into in the first place, and then delete the dummy admin account afterward.
Edit: Remember to only use this disk on computers that you, yourself own, and administer. Using this disk to access computers other than your own and is illegal, and neither myself, the other moderators, or any employees of BestofMedia will be held liable for its use or misuse.