Both places have configurator that will lead you through the process of finding the correct size, and type, of RAM for your machine.
Both places offer a Lifetime warranty on their RAM
Hope this helps
i have a G4 powerbook 3 laptop and have been looking for PC 100 or 133 SDRAM 200pin (2 x 512MG or 1G)... is this the correct RAM does anyone know where i can find it??