Check the advanced settings (right click on the mic from the control panel), and turn on monitoring (or whatever they call it now...) to allow the mic to be played back over the speakers.
Once this is enabled, check the green bars next to the mic in the Control Panel view, and see if they move. If they are, that means the soundcard at least thinks its outputting audio. If not, then the mic isn't picking up anything.
Could you please specify what option that is to monitor it, I cannot find it.