@whabang
What are you asking about? encoding (audio -> mp3) or decoding (mp3 -> audio) ?
topic is about decoding, while in the text body you ask about encoding.. /me confused.
Anyway, I haven't heard of a soundcard with hardware mp3 encoding. Also decoding mp3 takes only few percent of CPU time so it's questionable if it makes sense to put this on custom hardware on a soundcard.
Yes, I don't have a clue about SBLive! ;-)