Software firewalls offer basic defense from outside and inside attacks. In addition, they let you move from network to network. Hardware firewalls provide an additional outer layer of defense that can more effectively hide one or more connected PCs, blocking miscreants via a secure, dedicated platform. Both types are important, but we won't lie: Even the best firewalls aren't a walk in the park to set up and maintain.

Hardware firewalls are generally considered network appliances. The solid yet basic D-Link DI-604 is so inexpensive that you should consider one even for a single PC. The Linksys Firewall Router costs more but has very good networking features, such as true VPN and DMZ capabilities.