I have been looking at ads for an external drive and come across this kind of drive a few times: D2 Extreme triple Interface External Drive. Other than being more expensive and ad says it's the speediest transfer, should I spend my money on this kind of drive rather than just a Firewire? Keep in mind that I have a G4 iMac (one of those domed ones) and don't know if my Firewire drive would benefit. Jane