My computer has Ubuntu and Vista and I use both equally. I want to know if it is possible to continue my torrent download from both the OSes. For example, I start a torrent download in Vista using uTorrent but the next time I boot to Ubuntu can I continue the download I started in Vista?
The easiest way is to mount your Windows partition from Ubuntu and point the torrent to the folder containing the partial download. Trying to go the other way around requires ext2ifs drivers and it doesn't always play well. Ubuntu comes with an NTFS driver built in, so it makes things a little easier :)
After adding the torrent to the Linux client, the file will be checked (may take some time depending on the size) and once the amount downloaded is verified, it will continue. I would recommend using the same client across OSs to streamline things a little bit. Deluge is a good choice and has encryption capabilities built-in.