P2P is good for sets - but only has a fraction of releases. And if you're gonna buy vinyl an MP3 is just a sampler. You can also use P2P to distribute sets and take the load off servers. For example if Tribe of Munt posted Bit Torrent links you can get content from other users.

On the MP3 distribution - here's a good list...
http://www.therecordindustry.com/rec...itelisting.htm