Is there a reason to believe that choosing Windows was a bad decision?<p>The bad decision was installing antivirus software. Otherwise, most any modern OS would be fine. This machine probably shouldn&#x27;t be connected to a network (if it was), the USB ports should be disabled; data can come off on burned CDs, autorun should be disabled, etc. That&#x27;s how you deal with IA concerns on a standalone mission-critical system, not by installing antivirus.