I have a Macbook Pro 4,1 Penryn 2.4Ghz with a NVIDIA geforce 8600m gt. Now on the apple box and under the OS X system profiler, it says that I have 256mb of VRAM. But I have installed both ubuntu linux and windows xp on bootcamp, and running under them the nvidia drivers say that I have 512mb of VRAM. Which of these is correct, I'm confused?