Paintpot,
For multiroom audio I would recommend anyone look at the sonos system (and have done so lots on this fourm)
www.sonos.com . I could rattle on and on about the system, but I will say that I have had two different multiroom systems in my house (origional one got blown in a lightning storm, and I replaced it with a sonos).
You can install it yourself, and it is one of the most userfriendly systems you can have. It works with wireless handheld controllers instead of wall mounted wired ones whcih most systems use, and in my opinion the wireless controllers are the best option. In reality, you do not need a controller in every room ( I speak from experience of having a 6 zone wired system with wall mounted keypads, to now what I have is a 6 zone sonos system with 2 wireless controlles).
All my audio is stored on a network attatched hard drive (cost 300 euros) connected to my sonos system.
6 zones cost me 3.4k (excluding speakers and cable), and I can add additional zones at my ease if I need to).
For lighting, security and heating controll look at x10, which is what I have also. A very good system, particularly for someone who is into a bit of diy (my electrician did all the mains installation side of this for me, he had never come across it before but had no probs with it).
You can do this all on your own, rather than go the expensive route of a professional install, which is pricey.
Pre wiring is the most importand bit.
You can easily integrate your lights, heating etc via x10 to controll all your devices over phone, pc, internet wap etc using off the shelf products and software.
Look at and [broken link removed]
No connection with any of the above sites, just a happy customers.
Whatever you decide on the lighting system etc, serioulsy look at sonos for your audio.
and as was mentioned earlier, lots of cat5 for media distribution, media centre extenders etc.
Wexfordman