I decided to download and run the freely available Microsoft Safety Scanner after reading Gregg Keizer's ComputerWorld article New malware scanner finds 5% of Windows PCs infected. There is a very large button at the top of the page that one can click on to download the Microsoft Safety Scanner, but there is much more on the page. Roughly half of the lower portion of the page contains links and details about Microsoft's Security Essentials product ("a no-cost service for genuine Windows PCs"). The other half of the lower portion of the page contains links on Windows security and links on the most common threats found on PCs.
The Microsoft Safety Scanner page states that this application is designed to run alongside already installed antivirus software. In other words, Norton, McAfee, or other software does not need to be uninstalled or disabled to use Microsoft Safety Scanner. After downloading Microsoft Safety Scanner, I only ran the "Quick Scan" option because that covers the most common threats and doesn't take very long. There is also a "Full Scan" option available, but it is warned that this might take "several hours" on some computers.
The next image shows the Quick Scan progress being made. By the way, don't trust the green progress bar. When it reaches the end, it simply starts over again. Reaching the end doesn't necessarily mean you're almost finished.
I was pleased to see that my currently installed protection software appears to be doing its job. The results of the Microsoft Safety Scanner were what I was hoping for: I'm one of the ~95% (at least on that particular PC) free of the identified issues.
These results show not only that my currently installed software protection package is working, but also demonstrate that the Microsoft Safety Scanner was able to run without conflict while I had my currently installed software running. In fact, my currently installed software protection suite notified me on the download of Microsoft Safety Scanner that it was a safe download (not malware).
Because I still have a paid subscription to a competing suite of protection software installed on all of my Windows-based computers, I am not downloading Security Essentials at this time. However, the sentence (quoted from Microsoft Safety Scanner page) "Genuine Windows customers get a complimentary subscription to Microsoft Security Essentials, the award-winning antivirus software that helps you protect your PC." regarding Security Essentials is worth considering when it's time to renew my subscriptions, especially for my older PCs.
My recommendation is that anyone with a Windows PC should download and run the freely available Microsoft Safety Scanner to ensure that they are not part of the ~5% affected. This product downloads and runs quickly (if Quick Scan option is selected) and is advertised to not conflict with existing software. A subset of these people may also be interested in downloading Microsoft Security Essentials as a permanent computer protection package. Unlike Microsoft Safety Scanner, Microsoft Security Essentials is NOT designed to run with other antivirus software and that other software should be uninstalled before installing Microsoft Security Essentials.
As difficult as it is to believe, I know several people with Windows-based PCs that do not have antivirus or protection software installed on their computers or who have allowed subscriptions to updates to installed protection software to expire for many months or even years. For these people in particular, downloading and installing Security Essentials seems like a good idea. I believe downloading and running the "temporary" (10 days) Microsoft Safety Scanner is probably a good idea for all people running Windows-based PCs.
I've helped several people clean up their systems after allowing protection software to get significantly out-of-date or after not having any protection software installed at all. It would definitely have been easier on them and they might have even avoided loss of their computers for hours or days and loss of data had they had software like Security Essentials installed. As a side note, I have also found helpful freely available tools such as McAfee Labs Stinger (or other McAfee free removal tools), Norton free tools, and information on viruses, malware, and spamware that is available on many of the protection software vendors' sites.
I believe that all Windows users should have protection software installed on their machine, particularly if they access the Internet (including downloading e-mail messages). The freely available Microsoft Safety Scanner should be run by all Windows users because it is fairly quick to run and does not compete with installed protection software. Windows users who don't have any protection software installed should install either Security Essentials or some other protection software immediately.