Is there any plug available to connect the three wires from a 5.1 pc speaker system which uses the green/black/orange cables to a headphone port of an mp3 player or a laptop? I know from the laptop ...

I'm only a minor tech enthusiast, but I know that this can be done if you have a pair of powered speakers and something like an IPOD or RIO Zen or whatever... does it work through a lineout type thing ...