You should be able to run it. I've got your machine, but with 1gig of ram. It's not the greatest gaming experience ever, but c'mon! It's running on a 5 pound computer!!
I keep most of the graphics settings at medium, and the animations off. I don't even notice that I'm not having the same experience as other people until I watch my coworker play on his work computer. Then I notice the smoothness of play.
But I'm quite happy with the way my little MacBook handles the game. You will be too, as long as you're expectations are realistic.