Legal Torrents – This is a collection of legally downloadable, freely distributable ‘net.label’ electronica MP3 files which can be downloaded using BitTorrent. The site lets you download huge archives of free music from various online record labels.
The Legal Torrent server provides the initial seed, and they supply ‘BitTorrent irrigation’ for all the files by keeping a high-bandwidth seed online at all times, thus ‘irrigating’ the Torrented bits to everyone at decent speeds. From there, everyone that grabs the BitTorrent client and downloads helps contribute more bandwidth, because BitTorrent utilizes your unused upload bandwidth.
All the music is free and legal. You need to use a BitTorrent client to download the files. The files are huge, 200+ mb, so the BitTorrent client optimizes the downloads by sharing bandwidth among connected clients.
Synthtopia has instructions on downloading and installing BitTorrent.