Did you try installing the SB 5.1 XP
drivers in compatibility mode?
If they didn't work, then try to troubleshoot the realtek card... Go to device manager and try to find your Realtek card.
You Realtek sound card should look something like this:
If you find the card, you can either attempt to update the
drivers via Windows, or you can go to the Realtek website and download the latest HD Audio
drivers and install them via their exe file.
EDIT: Apparently some people have had success using this card w/ the Sound Blaster Live! drivers. If the installation gives you an error the first time around, tell it to reinstall and it may work.
http://social.technet.microsoft.com/...-e2e04aca203a#