For a 486 the Millenium II is the right choice in terms of period - I have the same one in my AMD X5 PVI-486SP3, it works great.

I'll try to stick with the G100 for its multitexturing and tolerable bilinear filtering. But of course, as the G200 couldn't run on this particular mobo, the usage of G100 may result dead as well...Then I'll consider using the other two, gotta find some more info on the Mystique G220.

Mystique 220 isn't that great of a 2D board but it is surely far faster than a 486 can take advantage of. Millennium II is a tweaked Mystique 220 for the most part. When I've experimented with 3D on them, they both appear to have the same features and even display the same quirks in their output. The differences probably amount to a better DAC, WRAM and maybe clock speed. The chips are MGA1164 and MGA2164. The 2D performance differences show up primarily in high resolutions like 1600x1200.

I actually suggest you avoid these cards. They are problematic because of a reliance on PCI DMA and of some driver tricks they use to boost benchmarks. Common problems include font and mouse cursor corruption, and instability in 3D. I get freezes in D3D even on 440BX and 815PE.

You might want to consider some S3 cards instead, for their superior DOS compatibility. The Virge GX/DX are as competent as a Mystique 220 for GUI acceleration. Virge tends to work in 486s too in my experience.