I heard formatting an external hard drive (with USB 1, 2, or Firewire 400 or 800) with Mac OX Extneded is good as long as you are only using that external HD for a Mac. But, is it necessary or recommended to do formatting as you can also use those external hard drives (maxtor, acomdata, and others) without formatting right out of the box. Does it lead to the file corruption if you use it without formatting. 