I need a video editing program that has the ability to cut out unneeded parts from a movie, and then save the file as a DivX AVI file (same as input file). I've tried it with movie maker, but it can't save in the divx format.
You could try VirtualDub. I am pretty sure, however, that once you edit, when you go to save you go through additional encoding, resulting in further loss of quality. Have a look at my signature. Te link is to a very, very helpful site. You will probably find what you need there.