Online Armor Personal Firewall is a top rated firewall for Windows (see Firewall leak test result and comparison chart here). It provides a remarkable protection from inbound threats and has complete control of data leaving your computer for the internet.
It’s powerful "HIPS" functions give you the ability to stop all unrecognized programs from running on your computer.
The release version of Online Armor version 4 runs on Windows XP/Vista/Windows 7 (32bit). Download the free version from here.