If you are interested in downloading free music from the net, like in the good old days of Napster, try this site: www.limewire.com
I have been using it for two years to download free music and it is easy to use and great. I think I have only searched for two songs in that time that were not there.
You can also download music videos. So if you have a special song you would like to hear again or want to see Michael Jackson dance to Thriller again, head on over!