rode make a semi decent usb mic and after all it is doing the same thing as a regualr mic, as long as it passes signal through to your computer and you aren't overly concerned about the quality that will be fine.
and as nicfit said try reaper.fm it is a billion times better than that audacity bullshit.
http://www.reaper.fm/
http://www.rodemic.com/microphone.php?product=Podcaster