spac13 I think his problem is that he wants to set the games to his monitors native resolution, otherwise its stretched.
You've done very well in the troubleshooting department. I have Crysis and a 22" monitor and I dont have this problem (i even have an nvidia card). 1680x1050 is shown in the list.
Did you notice any game option for "widescreen" displays? 1600x1200 is a 4:3 resolution, most notably square-shaped. Given your adept testing you probably already knew that.
Step 1. All I can think of is uninstalling your game and drivers fully. Then reinstall the drivers (all of them) then the game.
Assuming that fails, repeat "step 1" but this time try leaving your display (22" monitor) driver-less (plug 'n' play mode) and see if that helps. It might be your monitors drivers interfering with stuff.