Are you configuring the system for AGP 2.0 or 3.0, ie are you configuring dev 0.0 or 1.0? The way I had it set up, I thought, was 32MB for video, 32MB for agp, and the rest for the system, using AGP 3.0. I could very well have messed something up somewhere, though.
I'm configuring the system for AGP 3.0. AFAIK, frame buffer uses physical memory but agp aperture memory do not use physical memory. We could set agp aperture memory size to be 128MB even we only have 64MB physical memory. and I've disabled the integrated graphics card, reserving no memory for it.