My Matrox Millennium G400 wouldn't work unless I installed the VIA AGP Drivers. Win Me wouldn't even let me get to windows until I installed the VIA AGP Driver in safe mode. I think you should install the IRQ Routing also.
For the IDE Busmaster and VIA INF Driver, I never installed those drivers, didn't install it on win98se either. it keeps making my cdrom disappear whenever i installed the driver for IDE Busmaster.