You have done everything I know to do.By disconnect I suppose you mean the computer is only online when you actually need to be online? They can’t hack what isn’t there.
This is “disconnect”. http://download.cnet.com/Disconnect-for-Chrome/3000-33362_4-75645688.html
My XP computer will be unused and offline, it will only be needed if I have to look for advice to repair my new laptop, but I have hardened it as much as I could, to the point that I am thinking that I would be safe online even if I hadn’t replace it with a new 8.1 computer.
Here are some links for “hardening” XP.
http://www.microsoft.com/en-us/download/details.aspx?id=41138
http://www.thewindowsclub.com/secure-windows-xp-after-end-of-support-april-2014
http://windowssecrets.com/top-story/securing-xp-pcs-after-microsoft-drops-support/
http://www.foxguardsolutions.com/resources/details/xp-mitigation-techniques