5
As mentioned IceCast can do that and so can ShoutCast.
not sure of the options with Icecast.
http://www.icecast.org/If you go with a Shoutcast option, you will need to also set up something called SC_Trans this allows you to automate the music process.
All Shoutcast can be found at:
http://shoutcast.comYou will need ssh access and permission on your server/host to run services.
Keep in mind though that what every rate you broadcast at is multiplied by the ammount of listeners for example:
128k x 10 listeners
Could end up costing you some dosh, now if your broadcasting you may also need a music licence, depending on the type of music ie royalties or royalty free.
There are some companies like Live365 that offer shoutcast subscriptions (the music streams via their servers, so you don't need your own) that include a music licence, so you don't need to worry about the legalities.
Such companies may allow upload of your music and play them for you automatically so you don't need to worry about have Ice or SC running anywhere.
You could also consider Flash, something like Tufat flash player, it's pretty cool.
http://tufat.com/s_flash_mp3_player_mp3_component.htm(Flash could be run in the background via a browser?)
Hope this is of some help.