I think I already know the answer to this, but my optical drive on my 13"MacBook (OSX 10.4) is shot, and as an alternative I have been using an external drive (USB 2.0) that I inherited from my dad who no longer had a use for it. I was considering upgrading up OSX 10.5, however based on what I have read, I don't think that an installation from a USB drive is possible; only firewire. Anyone have any recomendations on how this can be bypassed, or am I stuck with 10.4??