I seemed to have the "jerky grafics bug" and i had tried everything here on site and numthing worked until i came across this tweak http://www.voodoofiles.com/7780 its a refresh rate tweak for the 41.09 nVidia detonator driver. Ever since my jerky grafics has gone away hope this helps you guys as i kow how frustrating it is to have jerking in games every 2 seconds

good luck and have fun