Make sure you are getting all of the discounts you are entitled to, on your homeowners insurance. Most companies give discounts for deadbolt locks, smoke alarms, non-smokers (you are less likely to burn down the house!), and of course a central alarm system. Some companies will even give a discount for motion-detector outside lights.
Call and ask -- there may be features that you already have that entitle you to a discount, or it may be worth the investment to install something, knowing that you will get an immediate return on the investment through a discount!