I'm getting the new Retina MacBook pro soon. I know I can't install Snow Leopard on the new Retina due to the hardware. My question is, if I have Snow Leopard set up on an external hard drive, will I be able to boot it that way, or will it just simply not work? I like to use Snow Leopard time to time just to compare differences between Mountain Lion and Snow Leopard, and I like to play a couple of old PowerPC games, so it's not a big loss if I can't run it on the new Retina through an external firewire (I know I would need the thunderboldt to firewire cable).