some good sites
www.isohunt.com
www.mininova.org
www.thepiratebay.org
www.torrentspy.com
basically you'll see an S and a number and an L and a number somewhere beside the name of the torrent. you want a higher S than L, and you want a lot of S if you want to make it go faster. S stands for Seeders and L stands for Leachers.