I really like the free ZoneAlarm version. When you install BE SURE TO CHECK THE 'FREE' VERSION box. I've used it for years. It's a solid product that is friendly to both the basic user as well as the advanced. It has intuitive controls, as well as more advanced capability. It's been heavily used and reviewed, and has maintained a strong acceptance rating throughout. The installation, use, and uninstallation has been clean and uncomplicated.
Some of the more 'retail' typical firewalls and 'security suites' are popular but can be resource hogs and can be problematic when uninstalling causing registry nightmares. I have not experienced any of that with the freeware version of ZoneAlarm. Also consider AVG or Avast as your free Anti-virus, and Spybot as your free spyware protection. Spybot does need manual updating but it is an outstanding tool.
License: Free Details...