At this price range, I think an Athlon II x2 or Pentium E6500 system would probably do better for pure gaming.
Both have more cache, the Pentium dramatically so. The Athlon II x2 would almost certainly over clock better, since stock speed is much higher, and most sites show them generally able to get to 3.8 GHz at roughly 1.4v or lower with a stock heat sink. On top of this, they use less power. So, more cache, 250 MHz more with stock heat sink (maybe more with a better one), and more cache against an extra core. Probably for games it would be better, but not always.
The Pentium E6500 is probably better still. Getting it to around 4 GHz wouldn't be too hard, especially with an upgraded heat sink, and is generally faster clock per clock compared to an Athlon II x2. Power use is significantly lower too.
Neither are clearly better though. I would rather have a faster two core than a slower three core, but the latter certainly have advantages too.