Does anyone know how many slots the current boards have in the mac pro, and if so, how many slots are free if you have the standard 2GB. I want 4GB in this machine when i purchase it, and i'm wondering whether i must buy 2x2GB and sell the 2gb that comes with it (as the upgrade on from apple is too expensive i would buy from crucial), or whether i can just add another 2GB myself. What form does the 2GB come in? 4x512MB, 2x1GB, 1x2GB? PS. Will it void the warranty by opening the case an installing crucial RAM?