Most of the Windows users prefer having a different firewall solution other than the builtin Windows Firewall. This has its advantages and luckily for us there are really great firewalls free of charge!
As of the writing of this article, the best free firewalls for Windows are:
Comodo - Best product in the free-firewall category with impressive performance and an easy-to-use interface
Zone Alarm - Extremely easy to use
Ashampoo - Good free firewall, but not as reliable as our #1 and #2 picks
Agnitum - Recommended by website visitors
Sunbelt/Kerio - The Sunbelt Kerio Personal Firewall will keep on working after the first 30 days, only in a more limited mode, but free