Next week marks the end of Microsoft's support for Windows 98 and ME.
An astonishing 70 million people across the world still use the older operating systems, which is about 13% of the total number of users.
However, as of 11 July, those people will no longer receive Microsoft's regular security updates, making them targets for all sorts of malware and hackers who know that flaws will no longer be patched.
Microsoft originally planned to discontinue support in January 2004, but extended it until July 2006 as a goodwill gesture to give businesses more time to upgrade their systems.
An analysts from Frost and Sullivan, Mukul Krishna, said, "The surprise is that they have continued their support for so long despite the fact that there have been many other versions of their operating system around since these version came out".
Given that the software giant is withdrawing its support for the system, it's expected that the number of users will drop to half the current total by the end of the year.
Many of the users are unlikely to be aware that upgrades are available, and they'll hang on to their OS until the system dies before replacing it.