You probably got the answers you want already, but if you want to really do some video editing, there is some professional software out there an availible that is open source. It's called
Cinelerra, and you can get it at
http://heroinewarrior.com/cinelerra.php3
Be warned, it's designed to be a pro-tool, so if you aren't trying to do something big, virtualdub would probably be a better choice. But if you are trying to do something big, you can set this up, and get the same floating-point pixel format, and image rendering farm abilities as the big guys.