Paul,

You may see two output devices listed, your
existing USB audio device, and the new audio over HDMI (HDaudio) device.
All that you have to do, is click the one you want the audio to come out
on, and that should be it.

Depending on your cunning with drivers, it might also be possible to
disable the HDMI audio entirely, and not give it a driver

Thanks for that. I'll keep an eye open for such changes, and change it back if
need be.

One other word of warning - the safe computing warning. While installing
new hardware is normally a seamless, and happy experience, sometimes
stuff happens. Make sure you have a backup of your C:, before installing
the new card. If you have regrets later, you'll have something to restore
with, and try again.

I use Drive Image from....
http://www.terabyteunlimited.com/index.htm

I normally uninstall the existing driver, shut down, unplug the old card,
plug in the new card, then use the new installer CD to do the job.
(That way, you don't have ATI files still running on your
Nvidia machine, or vice versa.)

I do the same, but also use Drive Cleaner....
http://www.drivercleaner.net/index.php
....that puppy can even clean various factory install files for ATI/nVidia from
MS .cab files!

Thanks for your help!