RedGage

Witcher II: Assasins of Kings needs good/very good pc for smooth gameplay. GTX 260 or better with 4-core cpu is ok for that game with high (but not max) settings.

First of all you have to check graphics settings. You will see many options here. If you are gamer, you know what is anti aliasing or depth of field, but what is "dangling objects limits" or "ubersampling"?

NOTE - this info based on one of the post on gamespot forum and my experience.

1 . Texture downscaling : higher values result in lower texture quality;
2 . Texture memory size : sets the amount of graphics card memory allocated to textures. Choose a reasonable value based on the amount of memory available on your graphics card (with 1 Gb Ram choose "large", ultra is for 2 GB or more);
3 . Shadow quality : affects graphics performance. Consumes GPU power;
4 . Number of shadowed lights : set the maximum number of lights that cast shadows. Affects graphics performance. Consumes GPU power;
5 . LOD distance : distance scale for level of detail on meshes. Lower values improve game performance but result in reduced detail on models;
6 . Bloom : effect improves quality of game graphics without placing excess demands on GPU;
7 . Light shafts : visual effect recommended for medium-high/high-end machines. Should be disabled on older systems;
8 . Anti-aliasing : demanding effect that can significantly reduce performance, so it should be disabled on medium and low-end machines;
9 . Blur effects : sucks in every game ;)
10 . Depth of field - gameplay: subtle visual effect. Option determines appearance of effect only during gameplay sequences and does not affect DoF in cutscenes;
11 . Vignette : option that produces a photographic vignette around the game screen. Does not affect performance;
12 . Rain, Wet surfaces rain effect : modest impact on performance;
13 . SSAO (Screen Space Ambient Occlusion): lighting effect that is important to the game but unfortunately places significant demands on the GPU;
14 . Motion blur : blur effect on camera movement, demanding on the GPU, sometimes sucks in PC games, sometimes not, but I'm not a fan of this effect ;)
15 . Cinematic depth of field : provides movie-like depth of field in cutscenes and dialogue sequences. Extremely detailed but demands significant power. Should only be enabled on machines equipped with top-end graphics cards;
16 . Depth of field - cutscenes : option only affects cutscenes and dialogue sequences, does not affect gameplay performance;
17 . Dangling objects limit : limiter for physical animation of character components like Geralt's hair. Disabling this option places greater demands on the CPU;
18 . Ubersampling : high quality rendering mode under which whole scenes are rendered multiple times to provide the best possible textures, object details and anti-aliasing (superior to anti-alias and anisotropy even on the highest settings). Use it only on top-end PC (for ex. with GTX 580 or similar Radeon card and very good 4-core cpu);
19 . Vertical sync : helps eliminate "screen tearing" during camera movements and blinking on very quick animations. Nice effect, but causes lags;
20 . Decals : enabling decals like dust or blood on characters can affect CPU performance.

I'm using these settings for smooth gameplay (30-60 fps) on my HD 5850 (805/1200 Mhz) and I5 750 (overclocked to 4 Ghz):

Gameplay(with HD):

http://www.youtube.com/watch?v=X3RWXNgiYL