i don't think the P has integrated graphics, hence runs cooler, OCs better and has more spare PCI-E lanes (i think) than the G, essentially, if you are going to be using any graphics card at all P is the way to go.
I've built and own both chips, 965G and 965P. The 965P is the faster, more versatily overclocking chip. I can't explain how the people at Anandtech managed these conclusions.