This is a very playable configuration that sacrifices very little image quality. Obviously, downclocking to 140MHz for stability made very little difference. 32 52.1 GPU set to 150MHz. My conclusions apply to my machine only. Other configurations may not exhibit the same characteristics.
Color depth makes a big difference in visual quality and speed.
Reducing geometric detail does not help much at all. I may not have tested sound quality fairly. At a CPU-bound low resolution, sound quality might make more of a difference. At high resolutions, where AGP and the card itself are the bottleneck, sound quality doesn't affect performance. I have not tried the A3D setting.