The posts that begin 'go to the range and try several different guns' and 'consider a shotgun' are right on. The part that's missing is getting training -- one is no more armed by virtue of owning a gun than one is a musician because you own a piano. (apologies to Col. Cooper for mangling the quote.)
You can solve this problem easily, however. You can get a list of local instructors from the NRA training division at 703-267-1430 , or by clicking this link:
http://www.nrahq.org/education/training/find.asp . Look at the basic pistol, first steps, and basic shotgun courses, and the home defense class. In fact, this last class is so good, I'd urge you to make a particular point of finding an instructor and taking the class. It gives you a ton of good information on making your home, and your family, a 'hard target'.
In fact, this last class is so good, I'd urge you to make a particular point of finding an instructor and taking the class. BUMP for Post 52 - EXCELLENT advice. Find an NRA course and ASK A LOT OF QUESTIONS!
Only then, should you make a purchase decision.