I am buying an iMac 24" 2.8GHZ next week with the standard harddrive. I decided on getting an external for all my crucial data and was wondering what is the best drive that can transfer data fast (firewire 800) and that can also be used for a pc just in case something happens with my mac for any reason and i'll still be able to access this data. What brands should I look at? I am looking at either 500GB or 750GB drives. I appreciate any help. Thanks in advance.