Call me stupid, but does my MBP have the ATI Radeon X1900 separate from the motherboard, or is it all one unit? The reason I ask is that I bought the 128 MB card in my MBP, but I would like to put a 256 MB in there eventually. i figured I could use the model they put in the 2.33 GHz MPB. Am I nuts on this? I couldn't find anything on the search so i thought I'd hazard a question.