Stumbled across this pretty sweet software product today while doing some research. CamStudio is a free, open-source (GPL licensed) screen capture application for Windows PCs. It can capture both audio and video simultaneously, allowing the user to record voice annotations along with the current action on the screen.

While CamStudio records everything in a proprietary codec, it is capable of exporting to both high-quality AVI and smaller Adobe Flash SWF files for web streaming purposes.

Their website is a little gimmicky looking and not incredibly easy to use, but scrolling halfway down the page will bring you to the product download links.

Give it a try and let me know what you think!