An interesting note. When I ran the regular game with Aero open, I lost 10-20 FPS, though still playable. Running with open folders and firefox with the benchmark had about a 10 FPS difference.
It seems interesting to me that having more RAM available increases FPS. Normally it takes a game that goes from a jerky mess to great FPS when I run low on RAM, but this game, having stuff open and taking away ram caused just a reduction in FPS, while still remaining smooth.
I wonder how this would play with 8GB or 12GB.