Comodo firewall

A free firewall program. I have not used it.

But Comodo's Firewall is unique in that it passes all known leak tests to ensure the integrity of data entering and exiting your system. Comodo has put firewall through all kinds of sophisticated tests to ensure its firewall powerful enough to ward off these attacks with default settings. No other firewall has had to work this hard. Take this test yourself.

http://www.personalfirewall.comodo.com/