I'm not sure of how the numbers/bus speeds would work in this situation, so I'm just going to ask away. How would the speed of a good 7200rpm drive on FW800 compare to one of the internal 4200rpm drives on the new PBs? Would it be faster for overall performance to install the system on the external drive than to use the internal one? I realize it'd be a pain, and I'm not planning on doing it, but I'm curious how it'd work. Any ideas?