Nowadays, you don't have to open Kazaa anymore to download music. A bunch of legal music programs is already online.
All three stores share the same basics: Tracks cost 99 cents, and most albums cost $10. Songs can be played on up to three PCs, transferred to an unlimited number of portable players, and burned to CD as often as you like, provided you occasionally change the playlist. They have comparable mainstream collections despite a disparity in total number of songs (more than 250,000, 400,000, and 500,000 for Musicmatch, ITunes, and Napster, respectively).