I gave World in Conflict demo a try, but it just crashes on startup. Supreme commander demo works no problems, so I might get the full version of that.
I had similar issues with the WiC demo. I grabbed the full game on sale and found that the numerous post-release patches to the retail code did a great job stabilizing and improving the engine. If you want the game and find it cheap somewhere it might be worth a purchase.
Anyone tried the BFME2/RotWK Triplehead mods in Eyefinity? The name says Triplehead but it should work for EF as well. It does have a stretched HUD and a couple menu issues IIRC, but is very playable. Learning some keyboard shortcuts could even enable gameplay with the HUD turned off most of the time. See link in my sig for the mods.