Depends on what you want to do.
Do you just want to crop a video with nothing fancy happening and be able to compress the video in to an avi file? If so then virtual dub is a good starting point.
If you want bells and whistles editing, cross fades, effects on the video stream and be able to turn that output in to a file / CDC ir you tube video, then try something like Serif MoviePlus
I got my MoviePlus X5 off amazon for £20 which is a pretty good deal considering that the latest version X7 is £99