I also have a PNY PCI 5200 (for about another week), and it's really a horrible card in my opinion. I've gotten to the point that I can't even stand to play the newest games on it because it is unbearably choppy. From what I've read, the FX cards weren't really optimized for DX9 as much as stretched for. Even low-level 9000 series Radeons demolish most of the FX cards in DX9 applications. There is actually a comparison around here somewhere... I haven't found a way to force DX8 on any games I have yet, but in KoToRII and FarCry, I set everything to minimum and still get that choppiness. Anyone know how to set up these games to run right? Well, I'm getting an x800xl this weekend anyways, so I guess it doesn't really matter.
Anyways, try running in DX8 mode, that should solve the problem. Sorry if I've rambled abit.