With respect to pairing a PC with a security system, I agree a standalone security system is the better approach. However, I'm not so sure putting all of the automation into an Elk or HAI system is the way to go as this would take longer to install and your code may not be as clean as it could be (e.g. one global script for Goodnight, in one single location: your PC's hard drive) and definitely will not be as versatile as a PC install. It will also typically cost more as sometimes expansion cards with specific firmware are needed to work with whatever serial module (such as the VRC0P).
Whatever PC program should be stable enough to handle automation tasks and not freeze up as these tasks seem relatively simple, especially if I can understand them! If a PC isn't reliable enough, I'd seriously question whatever automation program's design, because I doubt windows is the problem. This is one thing Premise has going for as there are no longer updates or changes to its SDK, and all of the bugs were worked out long ago before it was bought by Lantronix and then Motorola. Premise was also started by several microsoft employees, so it works well with anything microsoft (if that's what you're into).
Edited by etc6849, 07 July 2012 - 05:13 PM.