I've got two guns in the house and fully believe in them as long as the owners are responsible with them. I think Steve's definition of irresponsible is really dependant upon your situation. If you've got kids in the house, then yes, a loaded gun in the bedside table is not responsible.
I think the operative saying in your case is "it's people that kill people, not guns." As long as your trained and confident with your gun then you should be okay.
The one gun that I don't have and would like to have is a shotgun. I've heard numerous times that the cocking of a loaded shotgun in the dark of the night is enough to make an intruder soil his underwear.
