Google the word NTPASSWD and that's free.
http://www.lostpassword.com isn't so free.
I was given a computer by someone advertising a free computer. However when I got it home and tried to log on it was password protected. I have tried safe mode and that still brings me back to the log on screen. I have been trying to get in contact with the person who gave it to me but have been unable to. So now I dont know what to do. Can anyone help me?