1st Method:

The first thing which you check if you forget login password. When we install Windows, it automatically creates an account “Administrator” and sets its password to blank. So if you have forget your user account password then try this:

Start system and when you see Windows Welcome screen / Login screen, press ctrl+alt+del keys twice and it’ll show Classic Login box. Now type “Administrator” (without quotes) in Username and leave Password field blank. Now press Enter and you should be able to log in Windows.

Now you can reset your account password from “Control Panel -> User Accounts”.

Same thing can be done using Safe Mode. In Safe Mode Windows will show this in-built Administrator account in Login screen.

2th Method:

There are a lot of Windows password revealers and crackers available.

?

Windows password recovery tool:

but I?ve found that Windows Password Recovery Tool is the most effective.:
it not only supports XP, 2000, and NT, I have personally tested it with Vista Home Premium and Ultimate. It works perfectly to reset any local user account to a blank password.
http://www.windowspasswordsrecovery.com

You can use the ISO to burn a boot CD. Follow these instructions:

1. Download ISO file from http://www.windowspasswordsrecovery.com Windows Password Recovery Tool
2. Burn to a CD using a CD burning tool such as Nero or Roxio or MagicISO
3. Insert CD into drive and reboot.
4. You may have to select an option in the BIOS to get the computer to boot from the CD.

Booting up and clearing a password takes a minute or two works like a charm.

pwdump2:
http://razor.bindview.com/tools/files/pwdump2.zip