My friend and I both have VPC on our Macs. Mine is a G3 800 iBook, and his is a G4 1.25 ALPB. We were only able to give the VPC about 540 meg of ram because the program wouldn't allow us to opt for more. Of course, I don't have the option as I only have 640 in mine, and it would only let me put in about 400 something. He has over a gig of ram and he could only give it half. Can you give it more? I am about to get the PB and will get more memory if I need to.