Ranked as very good by PC World, PC Tools ThreatFire 3.5 Antivirus Software is a trustworthy internet security solution for those who seek safety online.

PC Tools' ThreatFire is devised to help users seeking online safety get protection from malware that has not yet been created. Unknown threats are a pain in the neck, and most of other internet security software companies have been thinking hard to eliminate the threats, but it is true that most of them fail. Kaspersky is said to be good at blocking new viruses that are absent in its databases, but this kind of proactive defense is not the strongest feature of Kaspersky Internet Security.

Free ThreatFire 3.5 utility is claimed to block a large number of threats through behavior-based analysis. During the tests, however, this security tool also caused some system lockups, but overall results are rather good if not excellent.

To start with, the software comes with 2 types of virus scanning: signature-based and non-signature. The signature-based scanner was added in the latest version and needs manual start or launch scheduling to run. ThreatFire 3.5 also features a world map showing where the threats come from and a system-activity monitor informing of the processes running on your computer.

While testing ThreatFire 3.5 ability to block malware using non-signature scanning (or proactive defense), the software managed to identify 90% of relatively unknown malware programs, and blocked about 95% of those identified and purged 90% of those blocked. This result surpasses the results shown by major internet security software. Moreover, ThreatFire 3.5 is way ahead other internet security software in correctly identifying innocuous processes running on the machine. Kaspersky's proactive defense cannot boast of such behavior.

Version 3.5 signature-based on-demand scanner does not ensure real-time protection, but activating the scan manually may help you find known threats in no time. In order to use it for free and get no-cost updates do not forget to turn on sending anonymous detection information to PC Tools. Remeber that you can use ThreatFire 3.5 free of charge for home use only (like Avast!).

The new system-activity monitor shows important information about current processes, their opened windows, the command line, the program author and other details. You may kill a process, or "google" it for further details.

Automatizing ThreatFire 3.5 notifications will make your life easier. You can set it to automatically quarantine, allow, or prompt whenever the software comes across a suspected threat or potentially unwanted program. This version of ThreatFire also has improved master boot record scanning.

The only drawback of ThreatFire 3.5 is reported to be a lockup on a heavily used PC with a wide range of installed programs and utilities when trying to run ThreatFire's on-demand signature scanner. So, if you use the program on a normal computer with average number of software installed, you should not experience any trouble as the program only needs less than 10 MB of system memory.

To summarize:
Pros:

• Blocks brand-new threats using non-signature analysis
• Monitors system activity in the background

Cons:

• Caused occasional lockups on a heavily used PC with lots of software installed

Bottom line: ThreatFire's complete non-signature protection ensures reliable additional security for your system. It is a good free extra security tool. It is also a good idea not to use too many security programs together with ThreatFire 3.5 as it may cause a system lockup.