http://www.tweakguides.com/NVFORCE_6.htmlThat gives more detailed explanations of all the settings. However, it seems everyone here knows most of this stuff (and thanks to the wonder of google, probably already has seen this webpage). Nonetheless, that may be of some use for some.
Just for fun, I think I'm going to see what happens with HQ mode.

(i'll probably be back in here in a few minutes saying how bad the framerate hit was).
EDIT:
Certainly, it looked nice, but I did notice a performance hit by going from 'quality' to 'high quality'. At one point, the framerate dropped to 25, and at a couple of other times, it was in the mid 30's. That's not horrible, but when it starts jumping from 120 down to 25, the experience comes off slightly ... uneven, I guess, for lack of a better way of putting it. I'll note that this didn't slow me down, per se. I mean, when I started with no video card, I was probably averaging around 25 fps, and I was still able to play through the entire retail campaign, but I'm not sure whether it's worth it to stay at the 'high quality' setting.
I guess my question is, what exactly is the difference between 'quality' and 'high quality' in the actual game? While I had the vague sense that it looked better, I couldn't really tell exactly what I was looking for.