I have edited my post, check it out. It includes a picture, you should be able to find a "Audio and Webcam configuration" menu, or something like that.
And as a P.S: you've posted in the msgplus! help and support forums, such threads should be created in the "MSN/Windows Live Messenger" forum. (http://shoutbox.menthix.net/forumdisplay.php?fid=10) since it does not have anything to do with plus! but with Windows Live Messenger.
Edit : No problem, and welcome to the forums!
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