What does the GPU do exactly? more specifically in regards to Aperture. I am running a 128 Radeon X1600 on my MBP with a 20" cinema displayed spanned for the large images and the MBP screen for the library. Before you ask, I only have 512 ram in the MBP right now as I am trying to wait until prices come down on DDR2 RAM. I know the RAM is a huge limiting factor. But will I ever notice the GPU slowing me down?