Well I hate Canadians (you can thank Shawn Michaels for that), but I also have an All-In-Wonder 7500 in the living room and would seriously consider another All-In-Wonder to replace my 4200 when it finally starts to show it's age.
Anyway, back to the post. You might try several things here. The first of which would be to make sure your game is patched to the current version, since this seems to be a problem with just Q3. You might make sure you don't have Quincux(sp?) AA set in the Q3 options, if it's available, since that is a Nvidia only setting.
You might try downgrading your drivers. I've often found that with Nvidia and ATI, the latest or best 3D Marking drivers aren't always the most stable or the most error free.
Uninstall the drivers, set the computer to defaults, and then install the drivers, play the game at default speeds and see if it is ocing related.
I noticed in your sig your 9700 is water cooled, you might want to double check the cooling to make sure the GPU isn't overheating.
I don't know how tweakable the 9700 drivers are, but you might want to make sure it isn't trying to force an AA or AF setting the game doesn't support.
Finally, and I know you've had to have done this already, have you installed a refresh rate fix yet?