Thank you all for the great information - I'm working on digging through it now, and checking out some of the links.
My initial goal is to replace my existing wired alarm system with a new system that I have more control over. Goals there are:
1) Utilize my existing wired sensors (all the doors, at least)
2) Be able to utilize new wireless sensors
3) Have it text-page me under various conditions
I'll expand on that as time goes on. I do, however, also want to eventually grow this into more than an alarm system. I've dabbled in x10 in the past, but want to be able to do more.
The ultimate, to me, would be a decent alarm system that I can programmatically talk to - maybe it fires off events or status codes that I can read via my PC programs. It sounds like Elk might give me that.
I have Visual Studio 2008 Pro - mostly I've programmed in Cobol, Pascal, and Visual Basic, but I do have C# and C++ available to me.