Any good free firewall like Zonealarm is more than enough, you have more chance of being struck by lightning than any body hacking your PC. Hackers are not interested in home users. When a PC or small business is connected to the Internet through DSL or a Cable modem and a router is installed, the router usually provides the firewall function that is sufficient to protect most small networks. Such firewall protection may need to be configured and activated in the router. This protection is sufficient (as long as the virus scanning software is maintained) to prevent a hacker from installing malware on your PC.