I am happy with my new 24" widescreen (1980x1020) I changed the lines in my conf.ini and changed my NVidia quality/performance settings so I can play full screen now with good FPS.
I have a NVidia 8600GT 512mb by the way.
But..when I use my headtracking device or my mouse to look around I get some distortion like you see in the image. It turns back to normal in a split second but can be annoying when you look around all the time.
What can be the problem or better said: what is the solution?

That's called Tearing. Go into the nvidia control panel and force vsynch on, you may need to turn triple buffer on as well, try it with or without.

With both options "on" it didn't work but with vsynch "on" I got rid of the so called tearing.
Thanx!