And also, a good Firewall is a must in some particular cases such as when you planning to host a website, connecting to a home or local network or playing games online, etc to protect against intrusion before they try to enter your computer.
To protect your PC against such security threats, you required to run a software firewall (personal firewall) on your system. Though Windows XP SP2 and Vista are comes with built in firewall, but have only limited functionality. Firewall from Norton or McAfee are well known but costlier.
As an alternative, you can prefer Comodo Firewall pro, which is a free personal firewall that is almost as good as the ones you have to pay for.
Comodo Firewall Pro 3.0 has a completely redesigned security rules interface. Users can quickly set access rights and privileges on a global or per-application basis using the flexible and easy to understand interface. The firewall also contains pre-set policies and wizards that help simplify the rule setting process.
Comodo Firewall Pro 3.0 added another critical layer of protection - Defense Plus, which is one of the most advanced Host Intrusion Prevention Systems available in any desktop security program. Comodo’s White List Database of over 1 million trusted applications or new applications that you specifically allow to be installed. This feature prevents most types of malware and rootkits from being installed and keeps a new PC virus and malware free.