hey bro, juz to let u know.

my friend's decent old rig has a C2D slower than yours (~2.3GHz), but he has a 9800GTX. He claims that the gameplay is quite smooth, maybe hovering around 30fps+ with occasional lag spikes, a few settings at high but mostly low. Not sure about his screen resolution though.

I cant be sure though since the smoothness is based on visual experience, which is subjective, rather than the actual fps given. But regardless of what you do, I hope that u stay away from alienware cuz' it's definitely not that worthy