A quick trip over to Net Applications reveals that Windows XP is still the second most-used operating system among all visitors to the more than 40,000 sites the company tracks worldwide (around 160 million unique visits per month). Its share of just under 30% or so stomps that of Windows 8, at just under 7%; Windows 8.1, at just under 4%; but falls short of the approximately 47% share enjoyed by Windows 7.
Still, it’s pretty clear that there are a wee more than a handful of users still clinging to Windows XP with but a few months to go in the operating system’s official lifecycle. While companies like Google and Mozilla have pledged to continue to support the OS after Microsoft’s cutoff — and, yes, you can still get an antivirus app for XP that isn’t Microsoft’s (for now) — it’s anyone’s guess as to how long Windows XP will hold up after April.

When Windows XP Dies, So Does Its 'Microsoft Security Essentials' | News & Opinion | PCMag.com.