Click the start button and type
in the search dialog box (<enter> means press the "enter" key).
Click on "Device manager"
Click on the little arrow immediately to the left of Sound, video and game controllers.
what audio devices are listed in this subcategory?
You can unload/inhibit the software associated with any device in this subcategory by right-clicking on the device and selecting "disable" from the menu. Do not select "uninstall" as Windows will detect the device on the next boot and reload the software automatically.
Alternately you can go to Control Panel > Hardware and Sound > sound and you should see two playback devices on the playback tab. From here you can choose default playback device. You may need to configure your preferred device.
Before I go on... I did get sound to work - it was a bad cable :-p but the fact remains, one would expect the onboard sound to NOT be detected by Windows if it has been disabled in BIOS.
I know how to use Device Manager, and I know I could disable the hardware there... and I did - but why is it even still being detected?
Because Windows does detection and initialization of certain devices, like sound, independently of the BIOS during IPL.
>>Because Windows does some hardware detection and initialization independently of the BIOS. But, you knew that.<< No, I didn't know that, and that has not been my observation.