i think it's the amount of system ram your onboard video takes
for example, if you have 256mb of system ram and your agp aperture is 32mb, that means you'll have 224mb of system ram and 32mb of video ram, since your onboard video is shared
yeah diablo got it right. In terms of the graphics not being onboard, when your graphics card runs out of Vram it'll call on that amount of system RAM that you set as the AGP Aperture
