The DVD files from torrents are usually VTS_VOB so you need to burn them to a dvd or use a player that plays VTS.
Power DVD plays the torrent downloads directly from a saved file. If you don't have it you can download a free trial here.
http://www.gocyberlink.com/english/p....jsp?ProdId=28
If you want to learn more about the whole dvd world you need to go to this site and read as much as you can.
http://www.videohelp.com/
It has everything you need to know to start working with dvds. It might seem overwhelming at first but if you read a little each day you can learn bit by bit. That's what I did.