Firewalls not only filter incoming traffic to your computer but they also increasingly help you to control the activities of Internet facing applications on your PC. The ones that provide the most control and security, typically require the most user involvement to answer popup alerts. If all the popup alerts are meaningless to you, then at a minimum remember to enable the windows firewall. In any case, only install one software firewall.
1. Comodo Internet Security
It has adjustable protection if you think it requires too much user involvement.
2. Zone Alarm Free Firewall 2010
It is an excellent inbound/outbound OS firewall solution suited for users of every level of experience.
Users can adjust security settings for their needs to allow for file/printer sharing, public networks,
and even turn off the firewall if ever needed.