I have a Maxtor One Touch III, 320 GB. I'm trying to back up my whole MAC computer (which amounts to about...a little over 100 GB...so too big for DVD's), but it won't let me delete or add anything to the harddrive. It'll let me copy things off it, but it won't let me delete or add. How do I change the settings? I have a PC I can use it with, so I can do the settings there. Or maybe there's an online backup place for free? I just need a LOT of space to back everything up for a while, since I have to redo my entire computer.