Hi zeeman,
I use Norton Antivirus 10 Corporate Edition. It has a 64-bit version avaliable, and has had so for quite a few months now. It runs fine and I have no issues with it whatsoever.
My router has a built-in hardware firewall. Because of this, I don’t bother with anything other than the default windows firewall in terms of a software firewall solution.
Cheers,
Kazesama