There is no real positive ending in my mind. If you're curious and don't wanna play again just go download radtools (search google) then view the different endings yourself. The movie files are in the game folder somewhere, shouldn't be too hard to find. Look for files with .bik endings.
I think I have played them all.
Now, i want to see if I can finish without killing anyone. But, it is pretty darn hard.
Any tips anywhere on the net or a place where folks who would try to do such a thing hang out and post?