I can tell you that in my professional belief that you were not hacked by a hacker using your IP.
I have delt with this from customers many times and the main cause isnt some random hacker with your IP, it is malware or spyware that is firmly rooted in your system sending your IP as well as all of your personal info to some hacker/shady dirtball.
In this day and age it really doesnt matter what OS you are using the malware out in the wild for every single OS from Windows to OSX is insane, and for those that are using any google products (running Linux)the new malware in the last month alone is over 500 new cases of malware that sends your info back to its creator.
You can get a new IP by swapping your modem out with your ISP, although 1 line of malicious code and it is all for nothing and you are at square 1 all over again.
If you have a wireless router from Linksys, Netgear, Etc. there is a nasty piece of malware that infects that as well(although rare)
What version of Windows are you using?
What antivirus are you running? (Most anti-viruses dont even detect the easiest malware)