itunes = shit, apple, DRM, restricted, defective by design, bloated
napster = lol no
frostwire = points for using frostwire instead of limewire, but it still uses the gnutella network. Since P2P depends on the other people, it's best to follow the trends. Torrents are all the rage nowadays, and superior to gnutella imo. You might want to try cabos over frostwire.
Torrents = assuming you know how torrents work, search
here,
here or
here for torrents. Specialty trackers exist, but you'll find those as you go along.
uTorrent is the most popular torrent client. Alternatives are Halite or
hTorrent which is a modified uTorrent with all the spying features removed.
You could also try your luck with good old
normal http too.