HyperCam is a free version of AVS Video Editor which will automatically determine the "best" codec for recording, supports audio recording and works just as well as Fraps (it's not very demanding).
It also comes in a 64-bit version if your hardware and OS support it.
http://www.hyperionics.com/hc/downloads.aspCamStudio is very demanding and Fraps, of course, is expensive when you may or may not have a budget.
