A good, free, easy to use movie-editing program?

I’d like to make some of my own little music-videos, setting scenes from movies to background music, things like that. What’s a good free program I can download to do this? Whatever all those people on YouTube use to make their cheesy little fan-videos of anime with pop music in the background or whatever - that’s what I’m looking for. What’s a good program?

Windows Movie Maker is free and worth a mention.