Well, with a firmware password, you are kinda out of luck over all. You will not even be able to install a new OS on it. The only real choice you have is to take it back to the school with your receipt and get the tech guys to remove the firmware password, and create a new admin account for you on the Mac with a password of your choosing. To me, having bought used/surplus Macs myself, I find it kinda shady that they sent it to the action without first wiping it and resetting it to factory conditions, or taping a piece of paper with the passwords on it to the Mac.