In an earlier post, Scot reported that Online Armor Firewall Shows Strong Promise. Online Armor isn't ready for Windows Vista yet. See Windows Vista Compatible Firewalls for links to free and subscription Vista compatible firewalls.
"I have learned directly from Comodo executives that the Basic Firewall installation option of Comodo 3 does not offer any outbound leak protection whatsoever. They may add that protection in a future version of Comodo 3.x. The Basic Firewall option turns off Comodo 3’s Defense+ HIPS module, which provides the leak protection for Comodo 3.
The previous generation of the Comodo 2.4 provided anti-leak protection without the HIPS.
Not only does this mean that Comodo 3 Basic Firewall is no longer a contender in this blog’s firewall evaluation, but if you are relying on this version of Comodo for your firewall protection, Windows XP users should switch to Online Armor FREE version 126.96.36.199 (or newer) and Vista users should uninstall Comodo 3 and reinstall it, choosing the “Advanced” installation option."
24Jan08 Edit Note: See Comodo Firewall Update