from what i heard most games will run on a dual core. battlefield wont it hardly boots on most dual cores but you should be able to play most on lowest, heck i play most games maxed out on a phenom triple core note its not a phenom II just a phenom triple core 2.1ghz cool thing is you can easily and cheaply upgrade assuming your mobo isnt like mine and will only use the processor it shipped with.
before i got my triple core i had a laptop with a single core 2.1ghz and i played all games on low but it ran star craft 2 and borderlands 1 surprisingly at 20 ish fps
Well, if you are playing multiplayer, it should go alright. Dual cores are not obsolete. I run a Celeron G530, and that thing plays almost every game I've tried to throw at it thus far.