Han shoots first. If he took the chance for greedo to shoot first, he may not have been there to save Luke at the death star and at Hoth, then Luke would be dead, Vader would crush the rebels, and where would that leave us? Without a complete trilogy.
I don't mind some of the minor editing stuff in the revised version (like couruscant at the end of RotJ), but changing that scene to make Han more "heroic" kind of made him seem like an idiot. I guess what I am getting at is that I liked it when Han shot first.
Oh yeah, Han is better.