[kraven]

If you're genuinely worried about having your home invaded, then why not employ a layered defense?
You can only sit in your easy chair with a shotgun in your lap for so long. Eventually, you'll need to take a shower, maybe go to work, cook, open up for the pizza guy... live.

If you want to not mistake the Police for the bad guys (and Sea Ray is right you are much more likely to have a criminal element invading) then why not install some motion detectors, a few web cams outside doors, etc.
The software for running multiple cams is pretty easy to figure out. Clearly you have a computer already.

Just being able to see outside your door in multiple angles is worth the cost. And, the cost is pretty minimal.

If you want to get fancy, you can tie it in to alert you by your PDA.
You could even build a saferoom with access to all the feeds.

If you're really worried about this situation, then take some steps to secure your home.