Your Iiyama LCD has a native resolution of 1280 by 1024.
From Wikipedia:
"While CRT monitors can usually display images at various resolutions, a LCD monitor has to rely on interpolation (scaling of the image), which causes a loss of image quality. An LCD has to scale up a smaller image to fit into the area of the native resolution. This is the same principle as taking a smaller image in an image editing program and enlarging it; the smaller image loses its sharpness when it is expanded. This is especially problematic as most resolutions are in a 4:3 aspect ratio (640×480, 800×600, 1024×768, 1280×960, 1600×1200) but there are odd resolutions that are not, notably 1280×1024. If a user were to map 1024×768 to a 1280×1024 screen there would be distortion as well as some image errors, as there is not a one-to-one mapping with regards to pixels. This results in noticeable quality loss and the image is much less sharp."
Basically, running at a resolution other than the native one has a negative affect on performance/quality.
As for settings I was asking what resolution you are running at & what level of anti-aliasing & aniso that you are using.
Possibly your in-game settings can be tweaked as well now that you have a better card.