There is a cool utility for allowing you to enter any password protected profile without any knowledge of the password. I have posted about Ophcrack (click here) that enables you to crack windows password. Well this method is even more simpler. Check it out at here.
Found this cool app, which will create a bootable USB flash drive and crack windows login passwords. It puts a custom version of linux on your flash drive and you just boot of it. I believe it uses rainbow tables to brute force and crack md5 hashes. It is not a full blown rainbow table, but the table is big enough to hold most common passwords.
You can download the app from Pen Drive Linux.