you have to get into your BIOS
press delete as when the system starts (black screen) and u'll find urslef into blue screen , means BIOS settings
you'll find their in On-Board Peripehels seection, on-Board Audio, simple disable it.
btw, i didnt myself lked the oon-board audio that came with P4C800/P4P800 motherboards, it sucks, isnt it?
Intel Core2Quad 2.66Ghz 12MB L2-Cache
4096MB DDR Kingston Hyper-X
XFX 9600GT AlphaDog
Seagate 2 X 320GB SATA2
LG L246WH Flatron 24"