Firstly be aware of where you stand legally...(you're the wrong side if its not obvious)
OK, disclaimer aside, you're adults who can make their own decisions
Peer Guardian will only really block IP addresses that belong to the 'other side' such as agents of the RIAA etc, it is in
no way 100% safe, whatever anyone tells you.
Your ISP can see whatever you are hoovering up at the time, whenever the hell they want to.
Most ISP will bow to investigations from the RIAA and Co and you will end up with a Cease & Desist letter....nothing to worry about in real terms, they are merely a 'shot over the bow' to tell you they know who you are.
If you've had one then either clean your act up, 'retire' for a while until you fall off their radar or 'up your game'.
Upping your game would be either encrypted FTP or SSL Usenet (everything you hoover up is encrypted and your ISP cannot 'see' what's going on)