How securely antivirus software has been configured varies widely between products with users of Microsoft's Security Essentials (MSE) the most likely to run protection using optimal settings, software certification firm OPSWAT has found. Using numbers crunched from PC's running the company's OPSWAT's AppRemover tool (140,000 installations), MSE systems had realtime protection enabled in 94.6 percent of cases, slightly ahead of Avast, McAfee and Avira.By contrast, Kaspersky Lab's Internet Security users only activated this important setting 65.5 percent of the time, with Norton Internet Security and Norton AntiVirus users not much better.OPSWAT shows 'virtual desktop' security system | Free antivirus grabs more market share, claims Opswat surveyMSE users were also the best at updating frequency, with 94 percent updating in the previous week. Just under 65 percent of For Norton AntiVirus and McAfee VirusScan users had updated in the previous 60 days, something that would render the protection offered by the software moot.When it came to systems scans, MSE again led the field with 74.5 percent of users having run one in the previous seven days while only a quarter of McAfee VirusScan users had done the same.OPSWAT doesn't speculate on the surprising variation in the settings applied to different products but the way people acquire software could play a part.Programs such as McAfee and Norton often come installed on new PCs with trial licenses and it is possible that owners are poorly motivated to upgrade to paid licenses when the trial is over, leaving themselves with under-configured protection.MSE is a free program users must actively choose to download and adopts optimal settings by default; realtime protection and daily updates happen automatically although scanning must be scheduled.OPSWAT also found that MSE is the most popular antivirus program in the US with 25.3 percent market share. Globally, it sits in second place on 13.6 percent, behind Avast Free Antivirus on 13.8 percent.Free antivirus software continues to slowly eat into the share of paid programs, many of which are showing gradual declines in global popularity.MSE has had mixed reviews with its protection matching paid programs in some general categories. Other reviews have the sort of detection issues that plague many products from time to time. What is clear is that basic paramters such as updating do matter.