Firewalls
Where to go for help. Everyone needs a firewall on their computer if it connects to the Internet. A properly configured firewall will not only protect your computer from intruders; it will prevent any unauthorized program or application from calling 'home'(Spyware!) There are a few free and quite good firewalls available.
The Comodo firewall is being recommended as the best firewall available, including commercial firewalls. Comodo is free.
Outpost This is also a very popular firewall.
Sygate was free but was purchased by Symantec and is no longer available. Too bad!
Kerio Personal Firewall This firewall has been purchased by Sunbelt and is no longer free.
Tiny Personal Firewall Another once free firewall, but has been purchased by Computer Associates.
A nice website providing information about firewall products is Matousec's page located here: http://www.matousec.com/projects/windows-personal-firewall-analysis/links.php
The Matousec page has logos by each firewall letting viewer know if there are free trials, what systems will the firewall work and whether or not they are free or part of a Security Suite. There is a lot of other information here about firewalls.
Zone Alarm free is no longer recommended as it may use scare tactics to get users to purchase software. While I have no objection to free versions of software suggesting users buy their products, scaring unsuspecting users is not a good idea.