Even though you would assume that people would know better, an anonymous reader writes, in my experience, I have found many who think installing more than one antivirus program on their computer is the right way to go about it. Some have installed as many as three third-party security suites, which among other things, takes a toll on the performance. This week the New York Times' tech tip section addresses the matter. From the article, which could be paywalled, but you don't have to read it in entirety anyway: Installing more than one program to constantly scan and monitor your PC for viruses and other security threats can create problems, because the two applications will likely interfere with each other's work. Clashing antivirus programs can cause the computer to behave erratically and run more slowly as the applications battle for system resources. Microsoft advises against running its Windows Defender security software on the same system with another installed third-party antivirus program. Likewise, antivirus software companies also warn against using other system security products when you are using theirs; Bitdefender, Kaspersky Lab and Symantec all have articles on their sites explaining the potential problems in detail. Programs that do not constantly patrol your operating system, like mail scanners, may not be an issue. What do you folks recommend to people who are not as tech-savvy?