Really a lot of great stuff here,
the NPR style really amazing, but render set was, in my opinion really nice.
The last shoot was impressive, the color gradient and the mood you achieved are very, very tasty.
Really a good job!!
Ciao
The first thing to do is install the latest drivers and see if that helps, often out dated (or the wrong) drivers can cause lots of problems.
As for a graphics card list, have a look here: http://groups.google.com/group/SketchUp/web/graphics-card-feedback?hl=en