If one were to put "deb http://http.us.debian.org/debian/ unstable main contrib non-free" in my sources.list, uh, I mean one's sources.list, then ran apt-get upgrade and watched about 200 packages get upgraded, what exactly would the result be on so and so's previously woody Debian installation? If a person had done this, is there any way to downgrade certain things back to earlier versions?