Before you dismiss the .410, you may want to look at the ballistics. A .410 slug at close range has more muzzle energy than a .45 ACP (check the ballistic charts if in doubt). The .45 ACP has proven itself over the years as an effective round, so that kind of power is nothing to sneeze at. Now, with that said, you are about to get blasted from some of the other members for considering anything other than a 12 gauge. Some will even tell you that the .410 is completely anemic. Again, check the ballistic charts and you'll see that the numbers simply don't lie. There have been many deer killed with the .410 over the years, so again, it's not completely anemic. The only real disadvantage that I can see when compared to the 12 gauge for home defense is the fact that the .410 holds fewer projectiles. However, I doubt anyone will really know the difference when hit center mass at close range.
There are also many studies that I've read that claim the .410 has the perfect balance in terms of power, penetration, and recoil when it comes to home defense. I personally wouldn't feel under gunned using one for home defense, especially at the typical ranges involved in home defense.
Now, again, prepare to get blasted. I've noticed that too many people buy into the belief that the 12 gauge is the only shotgun worth using for home defense. Don't get me wrong, the 12 gauge is a wonderful shotgun, but that doesn't mean that anything else is always the wrong answer. If you doubt the power of the .410, take it out and shoot it into some ballistic gel, clay, or whatever. Then ask yourself, would you want to be on the receiving end of such a blast.
Use what you have for now and if you're not comfortable with the .410, get something bigger later. Like you said, it's definitely better than nothing.