On Windows 7 (or Vista) I use
Outpost Firewall Free 2009 (2009/04/27 12:47)
Very popular Outpost Firewall is now also available in a lightweight version called Outpost Firewall Free. The previous free version of Outpost Firewall was released in 2002 and its protection was outdated for several years. The new free version is based on the engine of the commercial version with some features removed. Outpost Firewall Free offers Firewall, Proactive host protection and Self protection features as the Pro version but it misses Anti-Spyware, Web control, Identity Protection features and Multi-language support. This product may quickly become a great alternative for the users that require free solutions.