Well there's some free software out there such as Fraps which you can use for recording but programs like that tend to leave some form of watermark on the output.

Another suggestion is to get a Livestream account and record a broadcast. Also free and potentially better because it will allow more control over the quality of the video.

I've used Camstudio, and it's pretty nice--I have a small laptop and it ran very smoothly, plus the program itself doesn't take as much room as I had thought.