Just another question, I'm not sure what the data flow rate limitations for USB are but, would the max burn speed be limited to the flow of data through the USB port?
Your max burn speed will be limited by your device and whether or not you have USB2.0 ports. That's because USB 2.0 has a rated max speed of 480mbps (more realistically, people get between 50mbps and 300mbps). I'd suggest getting firewire if you have firewire ports on your pc. It's a bit faster and more reliable to work with over longer periods of time.