When you first boot the system, you should get a list of resource allocation. Right below or part of the system summary. Press the pause key and check to see if any two devices are using the same IRQ. Just because Windows is saying otherwise, dosen't mean that an issue isn't at hand. Check to see if the sound card is sharing an IRQ with another device or if it's using IRQ 9. Move it to another slot and see if this resolves the issue.
Not all, but on some boards, the top PCI slot shares an IRQ with the AGP slot and the bottom PCI slot shares an IRQ with the USB bus. Might want to avaiod these two. This isn't the case with all boards though.