ZoneAlarm is probably the most well-known of firewalls, partly because it's free for personal use, but also because it's effective and very simple to use. This latest version now works with Windows Vista. The download is a small utility that is used to select the correct version of ZoneAlarm for your operating system.
Its main appeal stems from the fact that you can install it and forget about it, yet be securely protected from outside intrusions or attacks.
Wizards make the installation as painless as possible, and ZoneAlarm will remember your preferences once specified.
In other words, give permission for a program to access the internet and it will always allow it access in the future (unless you specify otherwise, of course).
When in Stealth Mode, ZoneAlarm renders your PC invisible on the internet, increasing your security and privacy.