I am beta testing MixCastLive … it is working out very well right now.  The improvements from the first release to this one (0.84) are very impressive.

Here is a sample I just did: mcl2005-01-21_09.13.14.mp3 (803.6K)

I am having some issues on my home WinXP setup to get the Plantronics USB DSP-100 audio to play through the Realtek stereo mix.  But it seems to work great if everything is going through the standard Realtek audio ports. 

This sample is using a standard PC headset from Logitech called Premium Stereo Headset (#980185-403).