Some times back I have written article on using Rainbow crack to recover windows passwords. This article explains how one can crack any windows user passwords in seconds instead of regular brute force approach.
In short, Rainbow crack involves comparing the password hash with precomputed hash tables called rainbow tables to find the matching plain text password. As it involves just look up process instead of on the fly brute force cracking, it takes very very less time to crack the password.
To recover the password, you just need to retrieve the password hash as explained in this article and submit it to online rainbow cracking service.
There are lot of websites which offer free online rainbow cracking services.Here are few good ones…..
http://cracker.offensive-security.com/index.php (best one)
Now you don’t have to wait for days together with half hope to get back your lost password 🙂