Zone Alarm is free for personal and non profit use, I've been using it for years, and it's never let me down. I also have the firewall in the router turned on, but it's not stopping say exe or pif files from coming through, Zone Alarm gets those.

I also have anti virus software running, but consider that the last line of defense, just for things that get through the firewall and common sense.

I would check to see how frequent their updates are, hours can make a difference. If Symantec and McAfee have posted a upgrade today and they have not, it may be worth looking to a paid antivirus.