Comodo Personal Firewall 2.0 (free)

There has been a lack of freeware firewalls for some time now. Mostly due to them being bought out by larger companies and made into pay to use versions.

Last summer, PC Magazine rounded up free personal firewall products from Agnitum, Kerio, Sygate, and Zone Labs. (Symantec has since purchased Sygate and pulled it from the market; Sunbelt has purchased and rebranded the Kerio product.) They all did a decent job, though none was up to the standard of the best for-pay personal firewalls.

Comodo Personal Firewall 2.0 brings excitement back to the free-firewall category with a spiffy interface and impressive performance. It protects any Windows 2000 or XP SP2 system from hack attacks, and it blocks unauthorized programs from using the Internet—even programs whose malware-style trickery fooled the other free firewalls.

http://www.pcmag.com/article2/0,1895,1969207,00.asp