USB is too slow for an external blu-ray writer. However, there are a few externals that use TWO usb cables to connect, thus doubling the speed. However, IMO, usb is not a very reliable connection. I had an external dvd burner that had both usb and firewire. The usb connection would get me failed discs about 1 out of every 6 times. The firewire would never have any hiccups.