I hate to admit this given the forum, but I gave up last night on running this game in tri-screen goodness. I just couldn't find a good balance between eye-candy and performance. On top of that, the HUD drove me crazy. :-/
I do find it odd how poorly this engine scales to larger resolutions. The other games I've played so far took a good hit from running in such a large res, but this one is really amazing. Hopefully there are performance gains to be had by means other than settings tweaks and (some) eventual HUD fixes.
Good game though! I like how the guy who tweaks guns is a drunk. :D
SLI made a big difference for me. I ran it at 3840x1024 with everything cranked except AA. I was getting mid-20's on one 280GTX but almost double when I ran in SLI.
Finally finished it. I really love the STALKER series. So unique.