Firstly I can't tell you about the compatability thing. As far as your speakers it is more friendly than the SBLive.
Look in the Sound card section here for posts I made with links to articles.
I read in one review the the killer 5.1 setup would be 3 sets of Klipsch promedia's (2 speaker version). One drawback, the 2 speaker are $200 while the four are only $50 bucks more.
<b> Fragg at will!!! </b>