In terms of bang for buck
for gaming I dont think you should even be looking at anything less than 150-200 dollars so therefore imo one of the best bang for buck processors out there is the 8?00 range from Intel
http://www.amazon.com/dp/B00116SLYY/...Y&linkCode=asn
Intel Core 2 Duo E8400 3.0 GHz 6M L2 Cache 1333MHz FSB LGA775 Dual-Core Processor
Other products by Intel
Price: $164.50
I have a black edition AMDx2 6000 and I also have a AMD 3600x2 and i also have an Intel 8500, and they are worlds apart in performance. Some of the new AMD processors are really getting there like the Phenom II, but certainly last time I upgraded, Intel were WAY ahead, and I believe they still are at most price brackets.