Help Windows run what? Everything on a computer is a calculation.
A graphics card is a processor too, just a specialized one.
Uh, yes it is, that's not the point. ^_^
I meant to type "allocate and calculate what it usually does". CPU is processing scripts, all those things you mentioned are handled by the GPU. Unless of course we're talking Oblivion engine ini hacks, allowing for more AI scripts in more cells to be processed at the same time. Though that just means that the CPU is doing more of what it does - AI, physics, other scripts, and the part of actually showing it again is done by the GPU.