In reply to Gordon Stainforth:
> When you reformat it for the Mac, how do you keep the software that comes with it? Or failing that, can the Mac Time Machine be used to back up to both the desk top hard drive and the portable hard drive when away from home, without causing confusion/problems?
Not being a Mac user, I can't answer that I am afraid!
But if you want to keep the software, copy it off the drive on a PC then you can format and still have a copy.