Hi all! Running into a bit of a problem here.. Here are my MackBooks specs: 13.3" Macbook / 2.16ghz Core 2 Duo / 1gb DDR2 667MHz / 500gb 7200rpm / Snow Leopard. The problem im having is that im trying to upgrade the RAM. I currently have 2x512mb(1gb) RAM. trying to upgrade to at least 2x1gb(2gb) although i read that it can support up to 3gb or 4gb. I recently purchased 2x1gb sticks when i tried to install them both at the same time the computer would not boot, and yes i did read that you need to push them in pretty hard.. and i did!! I then tried just installing one of the new RAMs along with one of the old RAMs and the computer will ONLY boot if the new RAM is in the left slot.. I then checked my system profiler and it shows the new RAM but now both are running at 533MHz.. Im so damn confused i feel like my head is going to explode! HELP PLEASE!!!