I read all the posts in this thread, up until the Unlucky, Archie, Dude, clutch, gang bang and I have a few questions for the "shoot first" advocates.
1. What if it was one of the homeowner's children trying to sneak back into the home?
2. Why the **** could you not position yourself behind some sort of cover, flip a flash light on the intruder, and tell him your armed? If you are going to own a gun you sure as hell better have some idea of training on how to best protect yourself in your home, other than "if someone tries to open your door shoot the mother ****er". Just because you have a gun doesn't mean you grab it march downstairs and stand right in front of the door to make the statement that you'll shoot. This seems to be what most people are assuming one would do in this situation. Unless the intruder is carrying an assault rifle, you are most likely going to be safe behind a modest amount of cover.
I'm with Franklin and Viny on this one. I don't want anyone's death on my conscience, let alone a 19 year old kid, without knowing I took the measures to end the confrontation non-violently.