Some longtime PC users have never bothered with antivirus software, see no need for such programs, and have never encountered a virus. Some of these people even use Windows.
The cold, hard reality of the computer world dictates that most of us require multiple layers of protection from malware. Last week, I described how I removed dozens of Trojans and viruses from the family PC. The free program I used, Malwarebytes' Anti-Malware, is intended to be used in conjunction with a real-time antivirus program. Based on several comments, this point wasn't clear in the original post.
Another commenter suggested I write about online virus-scan services. I did that very thing back in May 2008 in "Your one-stop shop for online virus scans." I was glad to see that most of the services I linked to in that post are still available and still free. Unfortunately, you now have to register to view the results of Virus Bulletin's most recent tests of antivirus apps.
More disappointing was that the PC Flank scanning service I described appears to have gone belly up last month. When I returned to the site, Norton Safe Search identified it as dangerous. According to discussions on various forums, such as one on DSLReports.com, PC Flank went dark sometime this summer.
Still, nearly every major antivirus vendor offers a free online malware scan. It's best to stick with well-known brands in this regard because the scanner will access many sensitive areas of your PC. Some such scans are more intrusive than others, and most will detect but not necessarily remove malware.
Maybe if I didn't have to use Windows I wouldn't have to bother with all this security stuff—maybe. But I do have to use Windows, and I do have to use the Internet, so taking precautions is just part of the workday. Fortunately, if you do it right, it doesn't have to be a big part of it.