A quarter of all web traffic in May came from computers running Windows XP, despite support expiring more than a month before, it is claimed.
One in four Internet users relied on Microsoft's 13-year-old operating system last month, according to data from Net Applications, just 1.2% less than in April, when Redmond axed support for the aged OS.
XP is exposed to malware and other hacker threats now no new fixes for bugs in the code are being released, but that does not seem to have deterred too many people from using the operating system.
It appears that those ditching XP could be migrating to Windows 7, whose net web traffic contribution grew from 49.27% in April to 50% in May, remaining the only OS with a greater traffic share than XP.
Windows 8 held a 6.29% share last month and the 8.1 figure was 6.35%.
The news comes after a survey of 5,000 companies from security firm Bitdefender found that one in five SMBs were still using XP more than a month after it expired.
It found one web marketing business that had to tackle nearly 800 million malware attacks over the course of the three months.
Chief security strategist Catalin Cosoi said: "Swift migration from XP is a must for all users. A few weeks after the end of support announcement, a new Internet Explorer zero-day vulnerability turned into a permanent threat for XP users."