Of course the more power you get the better games are going to perform. As far as AMD vs. Intel (Pentium) you're not going to notice any difference, both are great processors for gaming. Although some seem to claim AMD is better for gaming than Intel but there is no basis or studies on it that actually prove that's true.
Quad core processor is the best right now but it's going to be a lot more expensive. I'd suggest at this time and date that you go with a dual core processor either AMD or Intel it's going to be the most affordable and best performance.
*Edit: Fixed spelling error.
