Electronic Alarms and Home Security Devices - New System

The house I'm buying will have a Ademco security system installed. From what I have been told, it will be hard wired installation. All doors and a motion detector are installed with a siren and a box that calls a security service if you sign up for that. Question is, do I need windows monitored and smoke alarm? What would it cost to add the windows and smoke alarm after I move in? They would have to be wireless because I'm not allowed to modify the system until after I move in.

Depending on the age of the house, it's a fair chance that your windows may be prewired, especially if it's of recent vintage. The system you are being quoted is the basic minimal system that many vendors install. So long as you don't have pets, it's functional.

Adding wireless depends on the system, but be aware that the individual transmitters can be expensive, especially in quantity. If it's within your means, you would be well served to have the windows at least properly prewired. Smoke detectors are well worthwhile. The ones designed for systems are much better than the ones that are used for typical hardware store grade.