With -nomtex added to the shortcut startup command, the framerate drop w/Vsync enabled is from 43.6 fps to 40.6 fps. Or from 55.8 fps to 50.9 fps w/Vsync disabled. The -nomtex flag does get rid of the mild stuttering when using the G450.
I also tested the G200 using the same driver version of 6.83 and want to point out that the G200 does not suffer from the same stuttering bug as the G450.
Concerning the Radeon 7000, the oldest driver I tested is the fastest, which is 4.13.7199. The newest driver, 4.15.9165 works, but frame rates drop by a small amount in most games. For example, GLQuake drops from 71.1 fps to 59.9; Quake III drops from 19.6 fps to 17.5 fps; Unreal drops from 20.7 fps to 17.4 fps; Turok2 from 29.3 fps to 23.1 fps; the Quake 2 score did not drop.
By the way, in case anyone was wondering how the Oxygen VX1 compares with other PCI cards on a K6-III 500, I ran some benchmarks with charts here:
Re: Best PCI VGA for a K6-III+ Cards compared are the GF4 MX440, FX 5500, GF2 MX400, Voodoo Banshee, Matrox G450, Oxygen VX1, Rage 128 VR, TNT2 M64, and TNT.