Microsoft Security Essentials, the free antivirus suite now available to consumers, is doing what everyone always anticipated it would -- shake up the staid antivirus market.

MSE, the successor to Windows Defender and the disastrous Windows Live OneCare suite, is a consumer-oriented application designed to detect and remove viruses and rootkits from individual home computers. It does not have the centralized management capabilities to make it applicable for even modestly sized business environments.

Early reviews of MSE are generally positive about its performance and effectiveness in stopping malware. As Computerworld reported, independent reviewers at AV-Test.org ran MSE through its paces and gave it an effectiveness rating of between 90 and 98 percent for detecting and removing various types of malware.

But that's not stopping the establishment from casting aspersions.

In a blog post, Symantec called MSE a rehashed application that lacks the performance and effectiveness to defend users against the ever-increasing onslaught of viruses. "The bottom line: Microsoft Security Essentials falls short of protecting against today's aggressive malware and zero-day threats," a Symantec employee wrote on the Norton Protection Blog.

The other two big antivirus vendors -- McAfee and Trend Micro -- have been silent on the MSE launch. Other vendors are offering mixed reactions to MSE's general availability. Some welcome it as validation of the "free to paid" market development model that many smaller AV vendors are using to build channel and market share. Others don't see Microsoft as a threat, but still question the wisdom of having the company that produces the underlying vulnerable platform also provide the antivirus protection.

"[Microsoft] will focus on gaining consumers through the simplicity of installing the product via routine channels of connection. On paper it makes sense, but in reality, we believe this will force consumers to unwittingly enter into a situation that makes them more vulnerable. Experts agree that the biggest nemesis to Windows was not the vulnerability of its code but rather the popularity of the operating system. It is a law of numbers; large communities create large pools of opportunities for thieves. If Microsoft leverages the power of its OS market to rapidly create a large community of MSE users, we believe those customers will be doubly vulnerable," antivirus vendor AVG said in an interview with Ars Technica.

But is all of this wrangling missing the point? Perhaps, and the real issue has a collateral impact on the rest of the Internet-connected world.

Let's assume for a minute that MSE isn't that good. Let's just say it's 60 percent as effective as some of the moderately priced consumer-oriented antivirus packages. Isn't that good enough? "Certainly basic, but free, protection is better than no protection," antivirus vendor Eset said in the Ars article.

As AVG noted above, the problem with Microsoft is and always has been its attack surface. It has such a large deployment base of its Windows operating system and applications that it's a favorite target of virus writers. Businesses and government agencies are targeted just the same as consumer home users, but consumer home users don't have the same level of diligence in ensuring the security of their PCs as even the most lax businesses.

All of the antivirus vendors have been running around talking about the explosive growth in malware over the last two years. The days of viruses that cause mass disruption are probably over, the era of stealth and targeted malware is just beginning. The volume of malware catalogued over the last two years is more than triple the total volume in the preceding decade. Providing users with antivirus applications that are automatically updated and don't expire -- even if they're less effective than commercial versions -- will likely provide a greater benefit than having no antivirus at all.

Perhaps the true measure of Microsoft's Security Essentials won't be the share shift away from traditional antivirus leaders such as Symantec and McAfee, but rather the level of threat reduction attributed to the suite by preventing tens of millions of consumer PCs from being infected by password-stealing malware and bots. With Microsoft's reach, distribution and marketing power, the day could come when all PCs have at least a basic level of AV protection, and that will definitely help squelch the threat level.