I personally use CamStudio to record things on my screen, and Adobe Premier Pro CS3 to edit them. Cam studio is free but premier you have to pay some dosh.
CamStudio is a great program, allows you to see what your doing on the screen without major resource use, has so many extra features but still persists to be an easy program and utility to use defiantly an essential in my opinion.
I have'nt had much experience with other free editors, but here are some all the same that I have checkout because of other peoples positive comments relating back to them.
http://www.virtualdub.org/download
http://www.avid.com/products/freedv/index.asp
Then use the free DivX to convert, resize shrink etc. your finished videos.
http://www.divx.com/