These services use many PCs as a great big network to download files. There is no way to insure the proper care and maintenance of these PCs. The end result being corrupt files downloaded to users. This is yet to be proven and is my opinion only. If you use these services ask yourself this...... how well is my or does my PC work? Yours PC will be one among many used in their network. My experience with these services has been .......... after a few files down loaded every thing went OK but the more I downloaded the more problems occurred till my entire system was a mess. In short, a bunch of minor errors adding up to serious problems. I avoid this services.

How these services works:

http://computer.howstuffworks.com/bittorrent2.htm