PC Tools ThreatFire Free
PC Tools Threatfire Free 4.7 won't replace your existing antivirus software, since it won't effectively clean up malware that has already infected your computer. What it will do, however, is excel at preventing brand-new threats from infiltrating your system.
Because of the way Threatfire works, we were unable to test it against our malware zoo of known threats, as we did with other software in PCWorld's 2012 free antivirus roundup. Threatfire doesn't use traditional signature files; instead, it relies solely on behavioral analysis--that is, it identifies malware based on how the invader acts on your PC.
That technology should make Threatfire fantastic at ferreting out new malware, and our tests bear that out. The tool produced outstanding results when blocking malware in our real-world tests: It fully blocked 92.9 percent of malware, and partially blocked the remaining 7.1 percent, the best showing of any free antivirus app we looked at this year.
As mentioned, Threatfire falters at disinfection: It detected and disabled only about half of the infections on our test PC. Because of this, it's best to install Threatfire on a clean, malware-free system.
Threatfire is designed to work side by side with most antivirus products, so if you just bought a new PC, installing Threatfire is a good addition to your setup routine.