if you play the game with the glide option and with nglide install - of course that is pretty much the only way to play with glide and it will give the best graphics, you can set the nglide game resolution through its configurator tool - it should be in nglides start menu folder
I have used it and it is playing the game at a much higher resolution -its great, i can use if on other 3dfx games like LB2 and play at higher res also