How big of a performance drop would I suffer if I installed and ran a game from an external UBS 2.0 hard drive instead of an internal 5400rpm laptop hard drive? The 40Gb HDD in my laptop is filling up fast and I have a 200Gb Western Digital Caviar in an external enclosure with free space. Would it make any difference if I connected the external drive enclosure using a Firewre 400 cable instead of USB 2.0?