I don't see how this will go into the audio port.Image
P.S. I just realized if I use my current speaker system it does not have SPDIF it has three 3.5mm cables that connect all the speakers.
That's an optical cable alright, but not the one you need. Go to monoprice and look at this:
http://www.monoprice.com/products/p...d=1022903&p_id=1553&seq=1&format=1#largeimage
And your speakers don't need optical, just speaker wire. The optical just goes to the optical input in your amp.
And yes, if you want home theater in two places AND the ability to do computer work in two places you need two computers. You can send media to a network capable TV, or game console, or computer but you need something on the other end of your network to receive that stuff from your Mac. How you proceed depends on how you intend to do that.
Maybe you should consider a simpler solution: get a MBP and move it from room to room. You can hook it to a HDTV in one room for the home theater, and use it with a second monitor in your office. Easy peasy.