I am the first to admit -- all of the items in this series are not stand-alone reasons to upgrade to Vista. It is, for instance, hard for me to imagine some business setting where the volume mixer would be the be-all and end-all solution that has so much business value that Vista is deployed without a second thought. Rather, I think all of these features (some large and some small) add up to provide a really great product. This is one of the small ones (but a great feature nevertheless). The volume mixer has been enhanced in Windows Vista; no more are you relegated to one measly volume control for every application. What happens, for example, when you want the volume on your mandatory training video a little louder so that you can hear it over the sound of your favorite tunes rocking out via Windows Media Player? (Let's face it -- the Privacy 101 course would be a little more interesting with Rockwell playing in the background. It's track 4 at that link. Hopefully, that takes some of the obscurity out of the joke.) Using Windows Vista, it's easy. Clicking on the speaker icon in the system tray brings up the master volume control. Clicking on the "mixer" link gives you individual controls for all the running applications using sound (as seen in the picture below). The individual slider bars let you adjust the volume of one application without affecting the others.
Just another of those little additions that make Windows Vista a great, user-friendly OS. (Provided you know it exists.) :)
Stay tuned. Lots more Windows Vista tidbits are still on the way!