I use Mc Afee security center with the antivirus set at level stealth.
It block everything !!
You have to set a specific port for downloading with a torrent program and the rest is completely hided.
before that i was at the normal setting and i got some package of virus who were able to pass over the antivirus and i was having to remove them with another program but since i am at the level stealth everything is perfect and i never have any problem with package of multiple virus who try to infiltrate your system at the same time .