I have several computers, with one holding all the music. I want to be able to broadcast the music so that the same music plays throughout my house. If anybody has any idea, please let me know. Thank you.
This actually would be a very difficult problem to solve unless first solution poster is implemented. The problem you would have is trying to sychronized all the music to same wall clock time. If you have ever tried to listen to Internet radio using two computer simulatenously, the mixed sound is distorted. Any kind of packet-based delivery would suffer from this problem - unless some sort of distributed time (NTP) and codec sychronization algorithms could be put together.
It's too bad Low Power FM is for non-commercial organizations and transmitters where not cheaper. You could create your own customized radio station that could be heard inside and outside - hopefully while putting away a cold one.
You can purchase a Linksys, NSLU2. I set mine up to host itunes and you can play all your music from any computer or Media device on your network. It works great.
I'm surprised nobody else has mentioned this, but have you looked at Shoutcast? It's a plugin for Winamp that lets you broadcast whatever is currently playing in your Winamp. Each of the other computers would then connect to the Shoutcast server, but as was previously mentioned, you'd almost definitely have synchronization issues, with each computer being a few seconds off from the others.
You might look into something like Windows Media Services, although that is probably more involved than you want to get. Another thing you could possibly "hijack" into working for you is Ventrilo. Ventrilo is typically pretty good about synchronization on a LAN and I think you could probably tell it to broadcase the output from you sound card instead of input from a MIC. Not too sure how the sound quality would be, but it's worth a shot.