Unless you can find someone who
a) got into the alpha
b) uses your exact setup
c) is willing to divulge the information somewhere other than this forum
you really won't know until you buy it and try it.
I am strictly an Intel guy, so I don't know how my 8 virtual cores compares with the 4 on that chip, but I don't think this game is as processor intensive as it does rely on graphics cards and your card seems plenty for the game. My rig ran 1.0 with a few hitches that I think were more due to the bad coding than anything else. Reports are the alpha client runs much better, but of course nobody can comment on that officially.