I currently have AH running on two monitors, at 2560x1024.
It works well enough, although the seam in the middle is annoying.
The main problem is that AH presents a square view box that the video card then displays as best it can.
At widescreen resolutions, like mine, or the triplehead, this means that the top and bottom of that box must be cut off to maintain the aspect ratio.
Now, I get around both problems with the TrackIR, although the TIR requires more vertical travel to cover the up/down range than it would otherwise.
Diche
