That's might pushing it. Depends on the settings. I have the sim and I ran it well with my gtx 295, ok on my 460m laptop and it runs well at max settings in 5760X1080 with 2 680s.
At the same time, I think the sim relies on the CPU significantly. I know that Flaming Cliffs 2 doesn't look as good but is more demanding and it's known that it only uses 1 core. I do think DCS uses 4 cores because it is better looking and runs smoother at the same time. If you turn AA off, HDR off, and run it with a 256 cockpit on medium - high with a low to medium draw distance that video card may be ok. What's the vram? Which cpu are you using?