I recently installed a Chaintech AV-710 soundcard in my HTPC which uses the Via Envy 24 chipset, has an optical SPDIF, and costs less than $25!

My HTPC is using a Biostar M7NCG-400 motherboard which doesn't have the MCP-T Southbridge, so no "Soundstorm" onboard audio. Sound was routed through an optical SPDIF and was good, but not as good as the sound on my other systems which have the "Soundstorm" implementation.

This little sound card is a great deal for the price! It supports 96KHz playback, which sounds superb through my Onkyo/Axiom setup.

Just wanted to give a "heads up" for any Axiomites in the process of building an HTPC who wanted great sound output for cheap!