Windows only: The popular Windows firewall application ZoneAlarm Free has a big brother called ZoneAlarm Pro, which boasts a handful of features not available in the free version—including integrated antivirus. Normally $40, ZoneAlarm Pro will be available today (11/18) for the low, low price of free. ZoneAlarm Free was voted one of the five best Windows firewalls by Lifehacker readers, so if you like what you've seen from that, a free upgrade to the Pro version sounds like a winner. The promotion link below will likely offer an active link to the deal starting 6AM PST this morning.
http://download.zonealarm.com/bin/free/sum/index.html