Okay, I'm sure this has been posted SOMEWHERE before, but I can't find it. I was wondering if you can use more than 1 External HDD with time machine? I have 2 500GB drives, and I have one that I use right now, but I'd like to use the other one for secondary backups, as in the ones that would be deleted when the first disk fills up. Is there a way to do that? Thanks in advance!