I have a 15' Powerbook G4 1.67, currently with 512 of ram....so i'm shopping for an upgrade, but not sure which specific type to go with. In my system profile it says i'm running.. Type: DDR SDRAM Speed: PC2700U-25330 And these are the types i've been seeing to choose from. G4 15-inch 1.67GHz (DDR M9676LL/A) Memory G4 15-inch 1.67GHz (DDR M9677LL/A) Memory G4 15-inch 1.67GHz Double Layer DDR2 (M9969LL/A) Memory so which one of those 3 is right for me? thanks.