Almost all software obtained via bittorrent from common tracker sites like Piratebay are just that, pirate.
You know this, don't feign ignorance.
The chances they contain viruses et al are high.
If you store any personal information on your desktop machine, like bank account logins, you are putting yourself at risk when installing hooky software. Regardless of whether you're running the latest AV/Antispyware/whatever crap you think you need.
If you are going do download executable content from anywhere make sure the source is reliable and you check the hash value of the downloaded content.