Just a side note, if you have access to at least one user account on the machine you can use the command prompt to change the password of any user account without having to know it in the first place,
just type "net users" (without the quotes) and windows will show you a list of users then just type "net user administrator 12345" where 12345 is the new password for the account. You can replace the name administrator with the name of any other account you need to modify. This should work on most configurations unless it has been disabled by your administrator as it is in most cooperate environments as you might have guessed.
I would also suggest creating a password protected secondary admin account so you can bale yourself out in the future if this should ever happen again, just don't forget THAT password, make it something you'll remember. My relatives lock themselves out all the time and it only takes a few seconds to get them back up and running using the second admin account.
-GrayWolf
but unfortunantly i dont know the admin user name either xD
