Forgotten Administrator Password

Source
I have often ran across computers that I needed to gain access to for data recovery, but I didnt have the administrator password to access the hard drive. Since in many situations, there is just one administrator account I can't log into another administrator account and change the password so I have to rely on other methods. I could put the hard drive into another computer as a slave and gain access (sometimes) or I could try installing a second copy of the operating system in parallel and gain access but there must be a better way.
That way is to try to reset the administrator password to something you do know and allow you to access to the user profile and the data. In most cases, this is the best solution. However, you have to make sure the data is not encrypted using the Windows XP Encrypting File System (EFS) or other encryption. If the data is encrypted, you probably will not be able to gain access to those encrypted files by changing the administrator password.
Petter Nordahl-Hagen's Offline NT Password & Registry Editor
This is absolutely one of the best free tools to reset the administrator password and gain access that I have ever used. It modifies the encrypted password in the registry's SAM file allowing you access to the account in Windows NT/2000/XP/2003/Vista systems.
There is an image file to create a bootable floppy disk or bootable CD to modify the admin password and access NTFS partitions. You do not need to know the old password to set a new one. It will also offer to unlock disabled or locked user accounts (a very helpful feature). The program was just updated on April 9, 2007 to include Vista support.
Please visit the site by clicking on the link below to download a CD image or floppy image of this great program.
http://home.eunet.no/pnordahl/ntpasswd/
LoginRecovery.com
Another option is to decrypt the password and show you the actual administrator password. A great site for doing this is loginrecovery.com. Basically, you download a small program to extract the password from the computer, then you submit the encrypted password file to their site and they will recover the lost password. Of course, you need a computer with Internet access to upload the file and find the password.
With this option, the administrator password is not changed so you wont lose access to EFS encrypted files. Visit their site by clicking below
http://www.loginrecovery.com
Although there are probably other options to recover an administrator password, I find the two option shown above to be the quickest and easiest ways to either change or discover the password and allow you access to the user profile and data stored on the hard drive.