FRAPS?
FRAPS is good, easy to use etc and they used to have an evaluation package but I think it'd watermark your videos.
CamStudio has serious issues. Even on modern hardware it won't record more than 10/15 FPS.
Personally, after trying to use camstudio for a few months I gave up with it. It has serious bugs/flaws, even for free software.
I just used it to make a promotional video for my work, recorded to full HD @ 30fps, encoded as xvid single pass with no problems whatsoever.
The resultant video is silky smooth.
Doesn't FRAPS only record in d3d applications, or something? I didn't know you could record just things you were doing on the desktop with it.