<< The 5.1 card has the ability to decode AC-3 (5.1)audio signals without an external decoder. The card acts as a decoder. >>
What a joke!
SB whatever doesn't have AC-3 decoder built-in.
You use the software dvd player with software AC-3 decoder to decode it.
what SB Live 5.1 different from previous version is just 6 ch analog out, so you can use cheap 5.1 speakers with 6 ch analog in, without spdif in and without built-in AC-3 decoder.
If you've 5.1 speakers with spdif in and built-in AC-3 decoder,
you don't need to buy SB Live 5.1, any sound card with spdif out is enough, the software dvd player pass the AC-3 signal thru spdif.