Some people may question the wisdom of employing a personal firewall on a desktop machine that's protected by a hardware-based firewall, in your broadband router or modem. For a single machine, there may be some logic in this argument. However, most home users have more than one computer - one for the kids, the other for parents and often a laptop could be brought from work to be used to finish off a project. You may want to enable your computer to be able to access the server at work, but you won't want to open up the port on your kids' computer.

ZoneAlarm Free 8 is the latest version of the popular free personal firewall. It would enable you to install this on a PC and configure settings that are specific for that PC, irrespective of how your router is configured.

ZoneAlarm link.

10 Sep 2008