Download the latest Nvidia drivers directly from their websitehttp://www.nvidia.com/Download/index.aspx?lang=en-us
Uninstalling current Nvidia drivers should remove the Nvidia HD Audio entries. Any that aren't removed once you've uninstalled the drivers should be right to safely delete.
When you install the new drivers they might show up again.
As you suggested I uninstalled the driver, then downloaded and re-installed it, but I still have to get on the net and see how it performs. I have noticed that now my Illustrator CS3 has a problem, some things are not working e.g. arranging graphics for one. This has happened since changing the Nvidia driver. How can I fix that?
One thing it is booting up much better.