using bittorent or another torrent applications doesnt harm ur computer u could use them without any problems and download only those torrents having more seeds and peers.
u could use some other antiviruses rather than norton in my opinion G-DATA is the best and AVAST could also be used ..
Bittorrent itself won't give you a virus. However, the programs that you choose to download with it could. You should always scan all your downloads for malware before doing anything else with them, and be careful about what you choose to download.