Is anyone here playing FSX with muti GPU's? e.g. Crossfire/SLI..

I've just ordered a new monitor, Acer 24" 1920x1200, and was thinking that the increased res may put strain on my current rig.

I'm using an HD4870 1Gb, and it performs pretty well on my current 1600x1200 monitor, but it could be better. (Rest of my rig is in the sig)..

Does FSX scale well in multi GPUs? If I add a second 4870 in Crossfire, would it make much of an improvement?

Thanks.