When I bring up disk utility and select the external hard drive (either the highest hierarchy of it, or the partition level) and click "erase" all the options are grayed out and non selectable. Is it possible to format an NTFS hard drive? Am I doing something wrong? any suggestions? I saw a youtube video where they said you could, but their options werent grayed out like mine are =/ Also, I'd like to use this external HD as my time machine backup drive - what format should I try to be getting it to?