I'm having the same symptoms.
sb live value
asus a7v880 mobo (viakt880/kt8237 chipset)
ati radeon9600
Disabled onboard audio in Bios.
Muted all audio inputs except wave.
Changed SB to other pci slot in order to give an unshared irq.
But the problem remains.
BTW, disabling smooth scrolling in IE reduces the amount of noise, but is not a real cure for the problem.
If anyone has suggestions, please tell us !