However if you want an alarm to cover your property and you don't want to disrupt your decor then a modern wireless system will do the trick.
I take issue with this statement, you have obviously never seen a 'professional' alarm installation, I'll not bother to say more.
ps Well done in resurrecting this 2 year old thread.
There are ways and means I agree and I defer to the skill of installers who keep wires out of sight.
Modern built homes make wired systems difficult due to chipboard sheet flooring upstairs and concrete floors with laminate covering.
If they aren't first fixed then it can't often be done easily.
Housebuilders are now skipping putting in the first fix wiring any more as people accept wirefree more readily.