Bought a new Macbook Pro 2.8 a few days ago (newest one with longer battery), it shipped with Snow Leopard. However, I believe the Hardware is still the same as before Snow Leopard was released, so it should work with Leopard 10.5. If I try to use a Leopard disc it just doesn't boot, or it comes up with a kernel panic. I even installed Leopard on my 2.5" in my Mac Pro first, then tried booting it on the macbook pro. Same thing, kernel panic. Have they added some kind of lock to the hardware that stops Leopard from being loaded? I thought they would only do that when new hardware is released.