My current hitachi drive works but it is pretty unstable. Games freeze sometimes but mostly it's trying to get the drive to read backups, it just takes forever. So I decided I should buy a replacement drive. Do I need to get the exact same drive or can I use any drive?

are your original discs freezing too? perhaps the drive isn't to blame? to answer your question though, you can get any drive you want. you will have to dump the firmware from your current drive and use that key, as well as setup the firmware to spoof the model number and report that it is a hitachi. (the flashing tools will do this for you, and there are guides in the stickies in this section.)