Wouldn't it be great if you could store all of your CDs in one place so you could listen without having to look for the CD? Yes
Wouldn't it be even better if you could take that central database
of music 
and
access it from every room in in your home?
Yes
Well you can...
There are a number of multi room audio systems that you can get installed
by professions. However, to date the DIY options and lower cost options 
have been scarce. All this is about to change
as new solutions are now on the market that allow you to use your existing
PC as a music library, these devices can then play the music around
the house.
Most will work using a wired or wireless network. We advise that you initially set these up using wireless and if practically put in wired (cat5) connections in when you redecorate a room.
So lets look at what you need
- A PC with enough hard disk to store your music (about 4mb a track if use MP3 at a reasonable bit rate.
- A wireless network router (many double us as ADSL Modems as well if you have broadband)
- A Music Streaming Device that either has a built in amplifier or one that will connect to a midi or hifi system.
- A hifi or midi system
Once
you have built your system you can then really benefit from music downloads.
There are a number of legal online music download services such as iTunes,
Napster and Sony Connect to name but a few. There are also a number
of file sharing services where you can swap music with other users.
However, beware the music industry are losing a lot of profit from this
and are trying to find ways of prosecuting users.
You can also benefit from the thousands of online music stations if you are on broadband which can stream music to your home from around the world.