A potential hack means nothing, when you start getting hammered from a specific ip for extented periods of time and multiple times, you can check
http://www.samspade.org on what is the abuse address of the isp, and email them about a possible hacked computer or a malicious user.
The isp will do something, or not.
For the time I've been in the internet with a always-on connection (3years or so) I've only once reported something to an abuse address (which was my own isps abuse, I was getting scanned 10times per hour from a lan ip).
So, generally you don't do anything with anyones ip, or their location.