I'm working on a hobby project that involves a Raspberry Pi (with a powered USB hub for reliable wireless), an Arduino (driving a hobby servo, controlling some LEDs, etc.), and an audio amplifier (not rolling my own - using a torn down set of powered computer speakers). So basically, I have five things that normally would each have a separate power supply.
I'm mostly a programmer with a little electronics knowledge, mostly digital with just enough knowledge to interface with sensors and things. I'd love for this project to have one wall plug, not be powered by four or five wall warts. I also don't want to have to implement a dedicated power supply. I know the Raspberry Pi is a little picky on its power consumption (I'm using a 1A supply for it currently).
I thought about using an old laptop power supply with 18v and (I think) 2A. Could I just do that and use a few power regulators to provide the necessary voltages to the other pieces? If I do, what should I be aware of and watch out for? I also considered an old PC power supply, but it's much too large for the enclosure that I have in mind.