You’ve listed Firewire 400 as being Slower than USB 2. Also the speeds you mention are wrong. Firewire 400 (400mbps) uses a different transfer method than USB 2. Because of this, even through USB 2 theoretically can transfer at 480mbps. USB transfers degrade over time, and Firewire is more consistent. Firewire does not require additional post processing either, like USB 2 does.
What about the Ethernet speed? Is it good to buy an external HD that has the Ethernet port?