Camstudio is the best free one and very easy to use. You can record with and without audio.
http://camstudio.org/Camtasia Studio is very pricey but their codec can be had for free on their website. Look for it. I think there's a clause in the licence agreement that you can only use it if you need to for compatibity with their software.
Basically if you ever intent anyone who has Camtasia Studio to edit your videos then I think you're all fine licence wise. I think... I'm no laywer.
Camstudio's own codec doesn't play well in VLC player, so that's why I recommend the above one.
I recommend you set Camtasia to pan so the file won't be so big. Set the panning speed on the low side.