According to Avast Software, a Czech antivirus company, computers running the decade-old Windows XP comprise a large number of infected PCs that have the ability to spread malware to other systems. In fact, 74% of all rootkit infections take place on a Windows XP machine.
From what Avast is saying, Windows XP computers are infected with rootkits out of proportion to the operating system;s market share. 74% of rootkit infection discovered by Avast were on Windows XP computers. XP only comprises of 58% of all Windows operating systems in use.
Windows 7, which powers 31% of all Windows PCs, comprised of 12% of all malware infested computers.
"According to our stats, as many as a third of XP users are running SP2 [Service Pack 2] or earlier. Millions of people are out of support and their machines are unpatched," AVAST stated in an interview.
So why is there such a difference between Windows XP and Windows 7? The answer is pretty much common sense. Avast believes that the widespread use of pirated copies of Windows XP compared to Windows 7's better security comprise the infection disparity between the two.
Avast even believes that those who run Windows XP SP2 didn't even bother to upgrade to SP3 due to them running a pirated copy of XP. Microsoft stopped support for Windows XP SP2 nearly a year ago.
Avast urged users running legal copies to upgrade to XP SP3. "Moving to SP3 is the most basic thing that should be done."