Go for i3 2100. Intel is best in gaming performance currently.
i3 hands down. Head over to the following link for further info. http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106.html
The PII 965 beats it when it's overclocked, and it's kind of silly getting a dual core now for gaming. More and more games are starting to utilize 4 cores.