Just wanted to share some quick advice. If you trying to record sound via video in Windows Vista you could be experiencing problems with the volume level for your microphone. Well you can try to adjust your microphone volume under recording properties to no avail where you adjust it to max or low and it doesn't change. Now I am not sure if this is just limited to usb microphones but the fix for me was installing Service Pack 2 for Windows Vista . After installation it gave me full control over my microphone volume. Hope this helps, enjoy.
Good catch. Sometimes no matter what you do it's hard to get a high recording volume with a USB mic. A quick fix is to use The Levelator. Or you could invest in a high-quality USB microphone.