I use Ophcrack as my first tool to reset passwords since it simply cracks the password and shows it to you in plain text (chntpw is my fallback method). Getting the existing password and using that (instead of overriding it with chntpw) ensures that files that are encrypted with EFS do not become unreadable.
In my experience, Ophcrack using the 'free' tables that come with the LiveCD has about a 50% chance of cracking passwords -- often within 10 minutes. You can buy larger and more advanced tables that have a higher success rate, and its probably a good idea if you have to do a lot of password cracking/resetting.
I, personally, use a linux distro loaded on a portable HDD with Ophcrack, chntpw, clonezilla, and a lot of other little recovery tools. Its fast (orders of magnitude faster than a flash drive) and versatile.
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