Which are the best mac compatible firewire hard drives? I'm looking for one that is ready-built and is likely to last me a good few years. I haven't got a price range but I'd rather not pay much more than $300. I'm looking ideally for a 640gb one to back up the internal MBP 320gb one. However, I'm open to suggestions of larger drives or smaller ones that are over 320gb should any exist.