In 2001 I was answering phones for a company that used OS2/Warp on the desktop, while I tried to find a technical job as the dot-coms crashed.
Warp was six years old at the time, and pretty terrible compared to then-modern alternatives. It was a dinosaur.
Legacy applications and the enterprise directory services infrastructure made the switching costs so high that it would be another year or so before they were able to switch to Windows XP.
Luckily the OS is becoming irrelevant. Ignoring the cloud ~computing~ marketing noise: cheap open-protocol traffic tunneling, multi-platform presentation layer client/server authentication and application projection, virtualization, and SaaS offerings are killing the OS market stranglehold. With this lower barrier to entry, expect fun innovations on the desktop. What will change with multi-touch projection walls or tables, universal wireless network access, e-paper, and irrelevant local storage and battery life concerns?
Actually, I’m just looking forward to not using Windows XP. It is a dinosaur.