I use torrent sites too, if u have a good firewall, i use Jetico and think its great! (apart from the annoying amount of times it asks for permission for this that etc) and good virus checker/spyware (i use AVAST and spybot,adaware and Xoft) u shud be ok with any. I prefer Opera for using the torrent sites, faster for me.
And as going to some of the sites u shud be careful if u go to crack sites etc a lot are full of viruses and spyware...