Yup, 12.04. It's because I'm using the NVidia driver for my externals, and Intel for my internal. No choice in the matter at the moment.
You try bumblebee at all?
Bumblebee solves the problem of using them together, and doesn't allow you to actually get 3d acceleration on the Nvidia chip. I just want to be able to easily switch between the two cards, but that won't happen, so the Xorg file moves will be necessary.