Low-volt home network

The aim of this project is to create a low-voltage network in my home.
I use a lot of led lights. They like low voltage, and I don't like mains attached adapters everywhere. Better to run a low-voltage line where they can be connected.
The first thing to decide is which voltage to use. The higher voltage, the higher current can be transfered in a given cable. But a higher current also gives more expensive regulators, so this has to be a compromise. 48 volts was the first choice, but is now changed to 24 volts. This is because there are a lot more regulators on the market that can be used with 24 volt. I also decided to use one segment per room to avoid too long cables and ugly wires all around the house. It also will be remote controlled by a Nexa-device. This can be controlled by a computer, which makes it possible to switch on and off the led-lights in each room separately with a computer software.

One of my led-lights (home built) uses a Pic-processor, and are build to be driven by 5 volts. To get from 24 volts to 5 volts there are some solutions:
-Build a regulator. A 7805 will do, but gives a lot of heat. A switched design would be better, but harder to build.
-A used car mobile charger.
-A Car usb-adapter. These can be bought cheap from Ebay and for example DealExtreme (I use this).

I had one mobile charger lying around (For use with Motorola V60), and opened it for examination. In it I found a IC called W34063, which lists as a "1.5A, DC/DC Switching Regulator". Good! The device from Dealextreme actually uses the same IC.

For power supply I plan to use a universal laptop adapter, also from DX. 24v/5A for $19 seems like a fair deal.