Runs pretty good on my crappy geforce2 32 meg and 256meg of ram, 1800 Athlon.
Everything set on maximum flashiness except terain on excellant, not perfect.
Cool game, best boxed sim out there to date, bar none.IMHO
Loads of planes, heaps of differant loadouts, and LOTS of stuff to shoot at on the ground, in the water, and in the air.
Great sound, awesome damage model and graphics, realistic cockpits. SEARCHLIGHTS

and a reasonably good mission builder/ editor (the FMB that is, the QMB is about as good as there has ever been for whacking up a quick fight to order)
More planes OTW too.
Try the demo for IL2 if you like what you find, you will love FB.