You can download a free Internet Security Suite absolutely free from Comodo. It includes Firewall, AntiVirus, Anti-Malware, Memory Firewall
Features
All-in-one Firewall & Antivirus
Defends your PC from Internet attacks
Detects and eliminates viruses
Prevents malware from being installed
Easy to install, configure and use
Free to both business and home users
Read more and download it here