Avast + a hardware firewall is the best combination.
Sorry Eddy, I have never agreed with that, as any malware that gets past your defences has free reign to connect to the internet, outbound connections sail back through your hardware firewall unmolested because the request originated from the system. Mind you you don't say what version of avast as the AIS has a firewall
Considering 1 in 8 infections supposedly come from infected USB sticks (according to avast iNews a little while ago). They don't have to pass through your hardware firewall and considering most hardware firewalls don't have outbound protection, you need a 3rd party firewall to cover that avenue.
Whilst we all know you can keep your system clean and a hardware firewall is fine for you, the same can't be said for the average user.