My wife and I just had this discussion, and luckily my brother-in-law is a State Cop so he could give us a better understanding.
I pretty much said, if a person is in my house without reason to be (meaning he's broken in) then I'm shooting. Not neccessarily to kill mind you.
My wife said no way, he'll take you to court, and end up taking everything we own just b/c that's how great the judicial system works around these parts.
So my brother-in-law's answer was as long as the intruder is placing you in a threatening situation (maybe life threatening). Not sure of the exact wording since it was my wife talking to him and her relaying the message to me.
Basically I got it as, as long as they had a weapon and where threatening you or your family shoot them. And his response to where to shoot them?? Right in the ol goodie box as to make sure they never reproduce again
Either way, I wouldn't be letting an intruder (armed or not) leave my house once he's in.