I have an MSI mobo, Athlon 1.4 (266 FSB), VIA Kt266 chipset (note: NOT the KT266a), I also run an SB Audigy and I have absolutely no problems with sound at all. I have the Cambridge soundworks speakers and use a splitter to plug my headset in. No problems with speakers (front or rear channel) or mic useage in any game I've played.
I do have, however, problems with the built in USB ports. I had to get a 4 port USB card in order to use my USB throttle. This is a known bug with VIA chipsets though. Something to do with not supplying enough power to the port for some devices. My USB printer works fine with the built in USB, just not my throttle.
I'm getting ready to build a new box to take with me to England (I just got orders there) and I am planning on the SOYO Dragon Ultra with the KT333 chipset, AMD XP 2100 and GF4 Ti 4400 (overclockable to ti 4600 performance easily). Although the performance gains are slight with the KT333, they are there none the less. Every bit helps.
Besides, for the minimal price difference, might as well go with it.