Online Armor
Online Armor is a relatively new firewall that is definitely worth a try.
Online Armor does a bang-up job of protecting your computer from attacks. Once you've installed it, there's no need to configure anything. The firewall has an ever updated list of dangerous programs and if any of these tries to get access to your computer, Online Armor will block it.
Truly easy to use and not at all invasive. Online Armor works with Windows 2000 and XP. A version for Windows Vista should be introduced by year's end. If you are looking for a firewall but are no techie, this one could be for you.