AMD Dual Core Phenom II X2 555 Black Edition, gaming?

Good.

especially if you can unlock it to a quad. just check the reviews of mobos to make sure they have ACC so you can try to unlock. AMD FTW!

well, that will depend on the game your planing on playing.

Some game will benefit from the high speed dual core. other's benefit from having 3 or more cores.

http://www.anandtech.com/bench/Product/83?vs=120

Personally I'd stick with going with something like the Phenom II x3 if you're gaming and overclock when needed. There nice cpus on that front.

Although only issue with that is, Phenom II x3's on newegg are OEM at the moment.  

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Well, it's good for now, but... i would get the Athlon II X3 445... great little budget gaming CPU.