in Motherbaord manufacturing and market share, here is the number:
BIG PLAYERS
1: Asus
2: GigaByte
after than comes
MSI
ABit
and others
VIA Chipset on PCI-E wasnt a tremendous performance leep over AGP version of same, so I'm confused, ATI's chipset for AMD Athlon performed better. so in case of chipsets, I cannot recommend one particular type now. but as if you have decided to go with VIA , then Asus is choice, and if with nVidia, then MSI makes performing Motherboard on nVidia chipsets.
rest, ATi's still to come (in a month or so)