In re the Soundblaster card: if you installed the card yourself, open the box and verify that the card is firmly seated in it's slot, and any cables emanating from the card are properly plugged in.
Second, if you have the hwinfo application installed, from the command-line, run '/sbin/hwinfo --sound'. It should identify both sound devices, and tell you which driver to load for each. Unload the driver for the on-board sound card (rmmod <modulename>) and load the driver for the Soundblaster (modprobe <modulename>).
I can't tell you anything about Raid.
www.google.com/linux is your best resource for reading material on that subject.