Yes, the model with the 1gb 6750 is crashing on source games. Haven't had it happen on Civ 5 yet. I can actually play L4D2 better through parallels than I can the native OS X version
That's with 2 cores and 4gb of memory dedicated to parallels though.
I thought it was pretty cool, but kind of pathetic at the same time. I Worried about it being heat related at first, but it crashes at times when temps are only in the high 70s.