db, if you have a microphone (which is the pimp way of making videos), then you should use Camtasia Studio. There's a free 30-day trial at
http://www.techsmith.com. CamStudio, while free, tends to create a lag between the audio and video as the vid goes on, making it difficult to watch.
You can get decent microphones 4 cheap, I have
this one. Sans microphone, CamStudio works fine for making a vid.