An alarm is probably worth the piece of mind. The alarm hadn't been installed yet when it happened to me. It was very soon after, and it made all the difference. The other thing that i learned from the experience is that the inexpensive locks that are in most houses are really easy to slip using a butter knife (my landlord at the time showed me, and it took him about 2 seconds- and he then replaced the lock and got the alarm installed). So, new, good locks would also be a good idea. But, i also don't live in the better parts of town...it would be even more disconcerting out in the country where you are.