OK, so you're going to need a Home Theater receiver, as it will be able to handle video switching and extracting and processing audio information from DVD's and Blu-Ray discs. In this case, the simplest solution is to hook a digital cable (either a single coax link with RCA connectors on each end) or a Toslink (optical) cable between the digital out on the sound card (most have both connectors) to a digitla input on the receiver (again, most have both types of connectors).
Then use iTunes or whatever software to "play" the music on the computer, which will be sent digitally to the receiver. You may notice better performance with lossless audio files (FLAC, WAV, Apple Lossless, etc) than with low-bitrate MP3's. You may also experience better performance with Vista or Mac OS rather than Windows XP. (Check the archives for this topic.)
Michael
Then use iTunes or whatever software to "play" the music on the computer, which will be sent digitally to the receiver. You may notice better performance with lossless audio files (FLAC, WAV, Apple Lossless, etc) than with low-bitrate MP3's. You may also experience better performance with Vista or Mac OS rather than Windows XP. (Check the archives for this topic.)
Michael