I haven't experienced it yet on torrent sites I listed above, but it is always a possibility. I had a nasty virus attack recently from some other website ( I guess one of the filesharing ones like rapidshare/megaupload, not sure). It took me almost a week to get rid of them, inspite of having mcafee. It took me a combination of mcafee, avg, hijackthis, windows defender and vundofix to get rid of it. Mcafee is the only one I bought, all the rest are freeware. I found avg pretty good. But that is off-topic.
I can't imagine getting hold of any of the rare movies from a mainstream rental like blockbuster. The worst part is blockbuster (as you know better than anyone) will not even stock nc-17 movies If I go to a local blockbuster and ask for cannibal holocaust, they may dial 911