recently a trojan virus aperently stumbled onto my comp. and my Norton Internet Security program told me that someone attempted to enter my comp and said he was blocked for 30 min. My normal Norton Antivirus couldnt find anything on the hard drive. But now im frantically trying to find out a way to  1. Find if hes actually got into the computer and 2. How to track him. Ive got his IP with me but i dont have a clue what do as ive never been put in a situation like this. Can anyone please help me?

Ive found out lots bout this guy in the last 4 hours or so. I searched him out using the IP and found out he lives in Australia,  and it gave me the P.O. box number. I restored my computer to an earlier date to see if the hacker can still get in...hopefully he cant. Finding out his ISP might be a bit harder than finding out where he lives though, but i think i can find out