Rendering problems (DirectX?)

I've had some problems with the graphics in some games and after asking around on respective boards with no luck I thought I'd take it here where there are programmers who works with this stuff.

Before I reinstalled Windows XP with SP2 I had no service pack installed and all was fine but after that I have run into some problems with some applications. The games I've noticed problems with are Thief - Deadly Shadows and the Dark Messiah demo. Some demoscene apps seem to have this problem too.
Symptoms I've noticed is that the vertexes seem to be off in some places, but I have no idea why.

Some screenshots:
http://img412.imageshack.us/img412/6793/wqu4.jpg
http://img406.imageshack.us/img406/3175/xnm8.jpg http://img406.imageshack.us/img406/884/yme5.jpg http://img345.imageshack.us/img345/4238/zvi8.jpg

I have a GeForce 6800 GT with the latest drivers and dxdiag says everything is fine. DirectX version 9.0c (4.09.0000.0904).