Following a long year and a half study, Scot Finnie named Online Armor 2.1 as the Best Firewall Software of 2008. Unfortunately Windows Vista users will have to wait a while longer. As far as I can tell, Tall Emu has not yet released a Windows Vista compatible version of the firewall.
See Scot's report at The Best Firewall Software of 2008: Online Armor. References are provided below for Online Armor help and Matousec's latest report.
Matousec Personal Firewall Leak Test Results
Online Armor Help Center
Online Armor Support Forums
The Best Firewall Software of 2008: Online Armor