Yes, buy a stereo receiver like this:
http://www.sherwoodusa.com/prod_rx4105.html#
You can connect 2 sets of inputs and outputs to it and switch between them with buttons on front.
In Walmart you can pick up "dvd player cables" and a Y shaped thingy that will turn left and right to 1/8 jack which you plug in the computer.
I have this set-up with 2 computers, 2 headphones (there is a headphone jack on front & I use a splitter from one 1/8 to two 1/8 courtesy of Walmart) and 4 speakers (2 sets of 2).
From either computer, I can play audio to:
speaker set 1
speaker set 2
headphones 1
headphones 2
together or separately, say only play on speaker set 2.
Or only play on both headphones.
I got the receiver at Circuit CIty for $80, plus figure about 20 bucks for 2 sets of DVD player cables and 2 jacks (that make left and right in one 1/8 plug).