Hi, new to this site. The house I just bought has an old FBI XL-2 security system in it, the previous owner said it worked but didn't use it anymore. It is hooked up to 4 doors and 2 motion sensors. I like the ideal of a security system but do not want to pay someone to monitor it. Is there anything I can do with this old system or is it worth while to replace the control panel and key pad and use the existing sensors? What do you all recommend?