Fraps is the best recording software ever created but it uses a locked codec so its codec wont work with Camstudio, only for playing back fraps footage.
The second best codec EVER created IMHO is PICVideo MJPEG. I used it all the time when I was interested in "Lets Playing".
If you google deep enough you can still find a legal free version, otherwise you must pay $28.
It's superfast and allows realtime desktop recording at 30 fps.
but remember the actual\final recording speed depends on your CPU and harddrive combination.
ALSO note, fraps contains a special audio recording system to prevent desync. No other recording system on the market contains such a feature (mine does but its been mothballed for now lol).
recording gameplay with anything otherthan fraps will always leed to audio \ video desync on windows systems over long periods.