"Of all those who use Windows as their primary system, 88.8% are using Windows XP. This surprised me a bit, as XP has not been around too many years. It shows that genealogists frequently upgrade their systems to the latest available hardware and operating system software."
Personally, I think the reason for such a high number of XP users is that Windows 95 crashed a LOT and Windows 98 wasn't much better. I still recall with some bitterness having to reboot Windows 95 multiple times on some days. Many days, actually. I never used Windows ME, but I can't recall hearing or reading much positive about that operating system, especially when it came to installation.
I've been using XP for three years and can't recall more than a few times that the system has locked up. It's even possible now to leave the computer on for days without a problem, something that I can't imagine could have been done with Windows 95.
One should also consider that support and security updates for Windows 95 was discontinued, and on June 30th of this year the same will happen to Windows 98 and ME.