Live Stream with HD PVR [Help needed]

I want to do a live commentary stream to a site like JTV or Ustream. Well I know how to do it with game sound. But the live commentary is the problem. The preview window lags behind my xbox and I dont know any way around that. I want game sound and my microphone synched with the game during the live stream.

The window lags behind like two seconds. IF there is anyway that I can purposely delay my voice that would be great. Anyone got any tips?