Zone Alarm - Free basic firewall for Windows

ZoneAlarm is an easy-to-use firewall that blocks hackers and other unknown threats and has the following features.

• Intrusion Blocking systematically identifies hackers and blocks access attempts.
• Stealth Mode automatically makes your computer invisible to anyone on the Internet.
• Automatic Program Configuration provides safety and simplicity by automatically configuring programs. Automatically decides whether to allow or deny Internet access to individual programs.
• Expert Controls give savvy users precise control over security settings.

Current version available for free and non-commercial use is 8.0.020.0 and can be downloaded from the authors website ZoneAlarm.com