Any computer that is used in a network and connects to the internet requires the protection of a firewall to guard against hackers and online attackers. ZoneAlarm Firewall, has proven to be very effective in protecting computers, even the free version adequately protects and prevents attacks. Among the common threats of this type is the cross-site scripting attack, this can happen even if you visit the regular trusted sites therefore no one can be too sure without a firewall.
Microsoft has an inbuilt firewall with its XP Service pack 2; however this only monitors inbound data and not the outbound traffic. With this loop hole, the installed firewall cannot detect a Trojan or keylogger that is sending out data from the computer. Some antiviruses come with firewalls but some do not, so one needs to be careful and ensure one is installed in the system.
ZoneAlarm Firewall is quite easy to install, even a person who is not computer savvy can do it, simply click next till finish then reboot to begin using. In order to use the program for free, select the Firewall version and not the security suite; otherwise it will be active only for 15 days when you will be required to buy the license. One can choose from automatic, manual and off in the alert advisor options.
One can manually configure this tool so that only the chosen programs can access the internet. This is the most effective way to deny access to the internet for Trojans and other malicious programs. Before allowing any program to access the internet, it will always ask you for permission.
The program is absolutely free but very effective. No other software of this kind can match the cost (free) and competence of this firewall program. It even works better than most paid version hence its top download status in several download sites.