ClamWin Free Antivirus isn't just free; it's also open-source, with no proprietary aspects. But in blocking malware, it doesn't get the job done. ClamWin doesn't offer real-time protection, and it won't check files as you access them; its scans are on-demand only. It missed almost half of the samples in AV- Test.org's zoo. Against malware made to steal online-banking passwords, it was nearly impotent, missing more than two-thirds of such samples. In proactive tests meant to find how well a program can detect new malware, it did better, nabbing roughly one-third of the samples while using two-week old signature files. But that still wasn't a satisfactory result.

Its six false positives were more than any other program save for Comodo Internet Security. It was the second-slowest app in scanning, and it put up the worst numbers for disinfection, detecting only six out of ten infections and cleaning only five. In a rare shining performance, it identified all ten active rootkits-but it did the worst job of removing them, cleaning up just four.

ClamWin adds a right-click option to scan a specific file-slowly-and by default it reports only malware; to get an option to clean it, you must change the settings.

Although running an extra on-demand scan can be good as backup for your regular antivirus application, ClamWin's poor detection rate means that you are better off running an online scan from a commercial software maker, such as BitDefender or F-Secure, and avoiding this open-source project.