HOW TO: Hacking Windows Vista Passwords
Most tools used to crack a Windows 2k/XP password haven’t been updated to work with Windows 
Vista’s SAM and SYS Hives, I decided to write this tutorial to shed some light on your options.
Before you run off and start cracking, do you really need to do this? I don’t mean hack the box, is changing the password a viable option for you? You can easily change the administrator password on 2k/xp and even Vista boxes with tools you would run from a PE boot cd, But there are several reasons why you might want to crack the password rather than simply change it.
1. They might be using EFS
2. If your auditing a system and don’t want to alert the admin. HOWTO: Hacking Windows Vista Passwords at Digital-Life-style.net