asio = 1 and only 1 device driver at one time.
You'd really be better off getting rid of the usb mic, getting a proper audio interface and regular mic(s).
Here's a good guide and tested suggestions that work:
http://www.tweakheadz.com/soundcards...ome_studio.htm
(you'll want to bookmark and read through all of Tweak's Guide while you're there...)