Broadcast
Create a Ustream.TV or BlogTV.com account (I personally recommend BlogTV for it's slicker chat, and more stable service). Ustream.TV and BlogTV are services that allow you to stream live video to thousands of people (if you can find thousands of people to watch) via webcam and/or capture card. Once you create your account you'll need to setup a show, customize your page look, etc. Spend some time playing around with all the features available and familiarize yourself with the chat functions so you will be able to moderate it during the show.

Once you have the page the way you want it, you should be able to select WebCamMax as the video source for your stream. Read the documentation whichever site you choose to use on optimizing your video quality.

Once you've got this set up and have a stream going, run a couple of test runs to make sure the setup will work once you go live. Check your camera positioning, video game feed, and microphone placement and play around with different configurations to find the optimal setup. Try to view the show on an isolated computer so you're able to see exactly what everyone else across the internet will see and make adjustments using that. Do some tests a few days before you go live, and another test a couple hours before just to make sure everything still works.