Password Cracker Win 7

I need a Password cracker to get into my friend computer to play a joke on him. he has win 7, please help

its a Desktop, Wired. just a simple password...

Not sure if it's what you want, but I found a simple code sniplet a while back that lets you change or remove the password on windows accounts.
All you needed to do is put it in a USB or a CD and restart.
I'll try to find it when I get home, and post it here.

Google Kon-boot