building a new pc

Now I'm not an expert oin the workings of the typical multi-core CPU, but Luthier and Oleg said there was support for multiple CPU's.

Now you have a 4 core processor. Lets say that Windows seven is being a big of a hog and is eating an entire core. You have three left, shouldn't those three remaining processors have enough processing power to keep 100+ AI aircraft and all the different ground objects in the air?

I'm sort of having a hard time comprehending something other than industry video rendering software or military level sims using more processing power than 3 x 2.5-3.5GHZ CPU's can offer.

Can someone school me here?