If you aren't going to carry, a Glock is hard to beat, easy to clean, reliable, stick with 9mm, no reason to go bigger, a .40 is a lot more kick but ballistically not a whole lot more of anything else. A .45 is probably over the top although I use a nice Colt Defender as my daily carry weapon but that's as much a personal choice as anything. If you are concerned enough to want to have a gun locked and loaded, then I'd recommend something single action so you can keep it cocked and locked and safetied and would maybe suggest a Browning Hi Power (if you have small hands this might not be as good an idea). The other thing about 9mm is it's a lot cheaper than .40 or .45 and easier to find now that everyone has gone into panic mode about ammo getting ubertaxed by Obama. If it's just for under the bed, I agree with everyone else, 12 gauge, mossberg 500, available for very cheap, very effective, doesn't require much practice. I have one for just such a purpose in case the wife ever needs it. Point and shoot, not much else to worry about, plus the smaller shot has less chance of going through interior walls and creating more havoc...