Even though many of the major AV companies will keep shipping signatures to XP customers, Marx cautioned against trusting that will be enough to keep old PCs secure.
"They may still be releasing signatures for the [antivirus] engine, but most of these companies will not update the product and the underlying technology [for XP]," said Marx. "Signatures are only one part of the AV story. AV includes a lot of different technologies, including behavior-based detection technologies, that may not be kept up to date."
But, he said, safeguarding an XP system with an updated AV title is better than doing nothing. "It's definitely very important to have AV, but people shouldn't expect too much from it," Marx said.
Microsoft has been sharpening its anti-XP knife for years as it has tried to convince customers to replace Windows XP with first Windows 7, then argued that they should just buy a new machine with Windows 8 or 8.1. When Windows 9 ships, they will probably switch to beating that drum.
According to metrics company Net Applications, Windows XP's user share -- the percentage of the world's personal computer owners who went online with that OS last month -- stands at 29%, a new low. But even though XP is on the decline, Computerworld has forecast that 25%-26% of all systems will be running the operating system at the end of April, and about 20% at the end of 2014.
Those percentages translate into hundreds of millions of PCs.
Most of those are in China by Net Applications' tracking, which Marx corroborated today. "Qihoo and Tencent said that two-thirds of their customer bases now use XP, and that it's impossible for their [combined] 300 million XP users to switch to Windows 7 or 8 anytime soon," said Marx.
Qihoo and Tencent are China's two largest AV providers.
Much ink has been spilled about whether Microsoft should extend XP's life by continuing to patch its vulnerabilities. Some believe that Microsoft owes security to those customers, even has a stake in keeping them safe since millions of infected Windows XP machines pose not only a public relations threat to Microsoft but to other Windows systems too. Others think XP is far too old to maintain, and should have been retired years ago.
Marx was in both camps.
"Microsoft has done a very good job here if you look at other market players," said Marx of Microsoft's 12-years-and-counting patching of XP. "I wouldn't blame Microsoft [for halting patches] but when no further updates for XP are available, think about what happens to the entire Windows ecosystem. It's going to be a real target for hackers and botnets. It will be a dangerous situation."
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is gkeizer@computerworld.com.
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