I use AVS Video Converter to prepare video to go on my Archos 5, that has an edit section that you could use, as would many other downloads of the web....
AVS isn't free, ubt the license gives you access to a raft of programmes, including an audio converter as well.
I doubt the video editor is the best out there, but I have had a quick play and it seems reasonably self-explanatory - can't give you a full run-down as I have not used it for more than 10 minutes to play around, but managed to selecte a protion of video and cut/edit it.......
I am sure someone else can point you in the right direction of other programmes and even free to download.
Google is your friend - do a search for free video editing software and see what happens