I would like to purchase a 15" PB combo. The only problem is, Apple is making it really hard for me to do. You see, I want to upgrade the video memory to 128, but for some reason, you can only do that on the SD model. I dont really think it is worth the extra 300 dollars for the SD model, when all you get is a SD and .17 GHz more, and you would still need to pay for the video upgrade. Anyways, does anyone know why Apple does this? It cant be a question of size. Is it supply issues? Will Apple maybe allow the upgrade later if it really is supply issues? Thanks for the input.