I like to take the car out more, but am afraid to let it out of my site. I'm interested in getting a basic (but not cheezy) alarm. What are you guys doing for alarms? When putting an alarm on an older car, are there any additional considerations (as compared to alarming a late model car)? What kinds of things should you look for (shock sensors vs activated by door switches vs ?). I am interested in spending about $150 - $225.