you can use THIS to remove the password from any account on a windows machine.
its a bootable image (burn it to cd with any software capable of reading & writing .iso's) and make sure that your cd/dvd drive is before your hdd in the boot order (in the BIOS)
just be careful with it, i can't remember the name of the feature but windoze can encrypt users documents with there password if you tell it too... all that tool does it remove the password, not crack it!
Yup, and if you change the password then all encrypted files will be unreadable. Of course, users hardly ever use the encryption feature, so it shouldn't be a problem.