OK heres the deal, I want to upgrade. So I am looking at ebay, crucial and here for RAM. So on crucial I go to check out what type of RAM I need fill in all the questions and heres what i get. when I click on the "ibook G4" I get PC2100 and when I click on the "ibook G4 12 inch" I get PC2700. How do I know which one is mine because I do have a G4 and it is 12 inch? Why are they different?