I've got an old imac that I want to rehab to give to my son's teacher for use in her classroom. The HD in the thing was giving off errors but instead of fixing it we just abandoned it and I set up a PC for the wife to get her email on. Any suggestions on where to start researching on what kind of drive it will take and and where to look for one cheep? Also, how do you get in the case on those things. Obviously I'm not a mac person.