directing audio output

I've been to a house where a single computer could actually direct audio outputs to specific rooms of the house, while sending another output to a different room simultaneously without the sound overlapping in the speakers.

I was wondering how this was possible; and if there is a reasonable priced way of doing it myself. Even if you don't have an answer, a point in the right direction would be very helpful.

Thanks in advance for any possible help.

Thanks for the quick reply, it has already proved to be useful.

sorry it took so long to respond, but that sounds perfect. is there always a way i can direct video output using the same concept?

I'm going to do a little research on this, thanks.

Yes it could, but it offers less control over the actual output then I'm looking for. A NAS would be a good start, and I have considered it for some time; yet I would like to eventually control each speaker individually, or each set of speakers individually from a computer connected to the network.