I have had excellent results with Zone Alert, bolstered by Ad-Aware and Spybot, so far.
You also can use Linux as your prime Operating System...and that should confuse him!
And I would write to Norton, and Microsoft, etc a snail-mail letter sent Certified, asking them for assistance. Keep copies! Aim high, even at least copy the Corporate President to assure attention.
Especially do not expect anything from Microsoft through their AI on-line functions...for them, AI stands for Artificial Ignorance! And I was never ever able to get to a real person on a major hacking problem. uSoft really does not care about individual small customers.
Have you tried the FBI? They have records of scams and hackers and so forth. And they might be very interested in a site that breaks all the normal safeguards.
Also write your Congressmen and inform them about this, and ask that since if this guy can hack you through normal security, he might be hacking the government computers also, and ask that they check and verify this for you.
Have you contacted your ISP? Mine I know will help trace the interference, and may put a block on their whole system for him at their front end..
Finally, contact F-Secure in Finland, and see if they know anything about this hacker. As they are big in both personal and industrial security, they might either be very interested, or have the cure, tho it could be expensive.
Changing to a MAC will perhaps cure your problem, but can you get the SW you need to do what you want to do on a MAC? They are very different in architecture and operation and software. And there ARE MAC viruses coming out, I hear, more and more.
There are a few virus gurus on the Net at various places that help folks with severe problems, also, if you can find them. Mostly associated with Anti-Virus companies. Be careful to check references; some may be virus authors especially if not with a known good company.
If you have a local Community or small college, and contact the head of the IT department or computer department, you can sometimes get good ideas, as they have to fight all of this for multiple users.
Might have to buy a cheap computer from them to load a really hot firewall and pre-censor all info in and out, as many of them do. One computer dedicated completely to anti-hacking for you, nothing else. You can often get good fast computers a couple years old for pennies on the dollar through educational ties with high schools and colleges.
Good luck!!