Click here for lots of optionsI've not used VirtualDub for screen recording, but in general I think it's pretty decent software. I only use VirtualDub as a free software video stabaliser for my videos, but it should be quite good for other things.
CamStudio seems to be alright too. I've used that once and it seemed to do just fine, but I didn't use it on anything too graphically intensive so I don't know how it will respond with games.