Pardon my ignorance... I've got a dual 500 G4 tower. Just loaded up RAM. I know the specs for my machine say that it will only take 1.5 GB. I have all four slots filled with 512 / 512 / 512 / 256 respectively. I'm running Jaguary and About This Mac tells me it sees 1.75 GB of memory. Is the computer really using that last 256 MB dimm, or does it only recognize that it's there?