Today, Microsoft stops supporting Windows 98, Windows 98 Second Edition, and Windows ME (Millenium Edition). (Washington Post link) Yes, these are old operating systems. But yes, a lot of people still use them. The computer I own came with Windows ME and it chugs along just fine, thank you.
Not that I run Windows on it anymore. About three years ago, I installed a variety of Linux on it. After about a month of switching between Linux and Windows, I dropped the Windows and never looked back. Not that it was always easy or convenient at first. But Linux desktop operating systems have matured in great measure in the last three years, and if you are looking to move on -- this is the time, and Ubuntu Linux 6.06 is probably your version.
I have come to appreciate the transparency its intellectually freedom gives, and the cost savings and product experimentation that the "other kind of free" allows.
I know it can be a bit intimidating to make that first step, but if you're interested leave a comment.