I have an Asus P4P800 mb. When I hooked up the speakers for the stereo in the back speaker plugs, it gave me an option for Quadraphonic, which just sounded like stereo X 2, with a mixer option. The Asus manuel states the mb has 6 channel sound and 5.1 sound, but they do not mention 4.1 surround sound. So anyways I am upgrading to an Audigy 2 oem soon and am also looking at speakers. Now the Altec 4100's are very cheap now, but I would rather buy the Altec 621 and use my stereo speakers for a back channel when gaming or movies. I prefer just stereo sound for music and I understand the 621 has pretty decent sound for music.
Did i mention that cost is a concern?