If you do get an alarm system consider motion detectors. I have seen a number of burglaries where the bad guy smashed a glass slider door and walked through it (never opening the door). The result was no break in the contacts and no alarm. If you live near other homes an audible system works well because when the alarm sounds most neighbors will take notice. Bad guys don't like to hang out where they can be noticed, so they will leave, hopefully without having had the time to look around for your stuff. A bad a$$ dog also helps
AL