Am playing Darkness Within 2 and am finding the movement to be very slow and choppy, I've tried changing the resolution but still no joy. Please help.

Usually slow, choppy movement either means your video card is too slow or that your drivers aren't completely compatible with the game? If you have onboard graphics or a budget video card, it's probably too slow. Have you tried turning off (or turning down) any "extras" in the Advanced Options menu, such as Shading quality, Shadow quality, or Glow? There should also be a "full screen effects" that you can disable under Video options.