Norton Personal Firewall provides excellent protection with avast. I used it for a year.
However, I no longer use Norton firewall for this reason: I paid £26 (that's $50!) one year to renew my subscription. There was a new version out which would have cost me even more. Norton promptly dropped support for my version, despite being happy to take the subscription. Shortly after they issued an update which broke the program, leaving me with no firewall and no support. Other people had the same problem, and eventually I found the solution on the net: reinstall, reinstall, reinstall.
Norton firewall is expensive.
Subscriptions are expensive.
Updates are expensive.
If you don't update you will lose support.
I've been using Kerio for over a year and it is very effective. I've just bought the full version from Sunbelt because it is so cheap. ($14.95)
Subscription is $10 a year.
Is NPF worth it?
In my opinion, no way!