Oh and the other difference is that the high res has a dual layer superdrive.

I honestly don't know the answer to that question.

Theoretically it shouldn't make any difference as they both use the same GPU, but knowing Apple there's probably some subtle difference that makes it impossible to use fit the high res screen. Apple are renowned, or should I say Steve Jobs was renowned for making it awkward and difficult for end users to get inside and upgrade the machines themselves. He detested the thought of someone getting inside and altering the perfection he felt the machine should be. In other words he ordained you to have what he wanted you to have and not necessarily what you wanted to have!