[All of the following is obviously based on my personal opinion]
The best public torrent websites:www.mininova.org
Excellent community which quickly identify poor quality/spam torrent files. Also, the search capability is far more accurate than ThePirateBay & IsoHunt.www.thepiratebay.com
The sheer vastness of torrents available is simply overwhelming www.isohunt.com
I found this site to be extremely good for downloading music and ebooks, but not films.
The pinnacle of Torrent search engine download however, is a site that can search through all of the preceeding, and Demonoid (redirects you to the Demonoid website search results, which you may then download):http://torrents.to/
An alternative to using a torrent search engine is to use Google by typing the name of the torrent you're looking for (If downloading music, I reccomend searching the name of the artist as opposed to the name of the song, if albums/disocgraphies come up, simple unselect the songs you don't want as your are adding them to KTorrent) then using any one of the hundreds of torrent search engines that exist and have been indexed by Google.
For help on using Pardus to download torrent navigate to:http://en.pardus-wiki.org/KTorrent