Every firewall is good enough. Zonealarm, in my opinion, is pretty good too. you can still be fooled even if you have the strongest firewall installed. It completely depends on how you monitor your network. For example, any executable file that is trying to access the internet can be bypassed if executing it from the command prompt because COMMAND PROMPT overrides all firewalls/anti virus. Batch file ( extension is = *.bat) can do it too. You do not really need a firewall as long as you keep your system updated/patched and watch what you doing/where you going. Have a good anti virus installed, thats better.
