I recently asked a genius bar guy this at an Apple store, and he said "I don't see why not". I'm hoping for a more definitive answer, before I shell out the bucks for Vista (which I will use for only 1 thing - using Netflix 'Watch Now' feature). Can I install Vista on my new iMac, but instead of putting it on the internal drive, put it on an external drive? I'd really rather keep Windows off my main drive if possible.