I just did the same thing for the same reason....I quickly found out that M audio will freak at any other internal windows things going on....for instance if your power settings are on anything but full power, sleep mode turned totally off... you'll get awful noises coming out of this thing.
Now I'm dealing with the fact that if I have the soundcard set to asio...BB doesn't see my usb microphone. It will work in the default mode but not in asio, which sounds so much better to me.