Comment 2 for bug 756474

Thanks, this should be fixed in qbittorrent_2.7.2+svn.r5435-0ubuntu1. You will be able to get it from my PPA within the next hour provided that you use Ubuntu Maverick or Natty.

Basically, qBittorrent now detects which files already exist at the destination when you add a new torrent. Files that were there before will not be moved to the .unwanted folder and will not be removed on torrent deletion, even though you ask qBittorrent not to download them. I believe this is now the expected behavior and it is a lot safer.