I don't know much about video editing software, but I've used Virtual Dub in the past for really simple stuff. It might suit your purposes, if you're not looking to do anything flashy. It's free, but you do get what you pay for. (Make sure you find some good codecs, though; the ones it comes were last I used it were crap.) Other than that, Sony Vegas is the only other thing I know of, but that's quite literally on the other end of the cost spectrum.