My favourite firewall in a new version Protects against Trojans, spyware, worms and other known & unknown threats. Prevents unauthorized or malicious applications from bypassing the firewall.Enables even inexperienced users to easily customize and fine-tune security policies.Provides best of breed evidence logs for intrusion analysis .Easiest-to-use PC firewall and still free for personal/home use Read More

I did not find a changlog yet but if you want to know the difference between these two version check out over here. Download Personal Firewall (Free)
Download Personal Firewall Pro Thanks to Fileconnect