It's currently too hard to find the Volume Mixer in Windows Vista. It is not
found as a result of a search in the Start Search control and it's not shown
in the control panel sounds section.
Suggestion: Modify the system so that the Volume Mixer application is shown
as the result of a search for that.
This post is a suggestion for Microsoft, and Microsoft responds to the
suggestions with the most votes. To vote for this suggestion, click the "I
Agree" button in the message pane. If you do not see the button, follow this
link to open the suggestion in the Microsoft Web-based Newsreader and then
click "I Agree" in the message pane.