[Wizard of Id]

Hi,
As part of renovating my house, I put in CAT5 cable around the house with no clear idea of what I would do with it, just thought better to put it in now rather than want to do it afterwards. Im using some of the cable to connect my desktop to my Orange livebox. However I understand that of my Cat5 I'm only using 2 of the 4 twisted pairs, and what I would like to do is connect the audio out of my PC to the unused 2 twisted pairs so that I can send line level audio around the house and have the stereos in the other rooms pick it up.

I suppose I could get a soldering iron out, attach a 3.5mm jack to the unused strands (once I know which ones they are) connect this to the PC audio out and then hook up similar 3.5mm jacks to the other outlets. Something just tells me this isn't going to quite work that way and there must be a smarter way of doing it. I don't want to ship video, HDMI etc... just straight stereo, any suggestions on how to approach this?

Thanks in advance.