I'm wanting to back up my recordings on my 722 to an external hard drive. I was wondering if it had to be a blank hard drive, or can I leave my computer files on it as well? I'm just concerned that when the receiver formats the drive that it will wipe everything that's on it off. It would take too much time for me to copy the files off and I don't really want to spend money on buying another drive, but if my files will be okay I won't worry about it. Does anyone know the specifics on this?