To start with, here is what I was looking for:
a) To be able to monitor my alarm and know if it is going off.
b) To be able to have a camera capture pics of any intruder.
c) My wife is profoundly deaf, I want to be able to record from TV and playback with subtitles.
I bought a new house a few months ago after losing my last one in the earthquakes..
I had previously had a DSC alarm with a RS232 interface, which I had connected to my linux box. I wrote my own daemon which enabled/disabled zonealarm based on whether the alarm was set, and emailed me on alarm or monitor detection.
I used http://ipipi.com/ as a email -> SMS forwarder.
I had a couple of old wireless IP cameras which I used connected up with zone alarm. I configured it to email 30 seconds of video, 15 before the trigger and and 15 after on motion detection. This went to a gmail account, and I would view the video from anywhere.
I had small web app I could use to arm and disarm the alarm remotely, it was over https and the arm/disarm passcodes where generated each day using a formula I could do in my head.
I used MythTV in the same ubuntu box with a satellite receiver card, and put a small frontend box up next the TV.
It was all working well, hardly any maintenance needed and it was all pretty rock solid.
Of course then we had the quakes and I lost it all.
We are in a new house now, and I am almost all set up again.
This time I have gone with a Paradox alarm with a very snazzy touchscreen keypad. There is an iPhone app to control the alarm, and one of the panel outputs has been connected to the garage door opener, so I can open and close the garage door remotely. This has already proved handy..
The Paradox panel has an integrated webserver and email, but I have yet decided how I will interface it to zone alarm.
I have yet to get zone alarm camera set up again, but I am almost there.
The only thing I wish I had done was put a reed switch on the garage door so I could make sure it closed again when I told it to.
The Paradox alarm system was supplied installed by Austin of Positive Security, whom I found very knowledgeable and interested in what I was trying to achieve.
[edit: typos, added into on web interface to DSC, kudos to Austin]