I am a big critic of the linux graphics stack and yet it is better in many ways to the pre-vista stack in Windows. The responsiveness of the stacking WM in Windows in awful. The reason people use XP is the applications. The applications on Windows are always superior, even the ones that have Linux versions.
So in other words people can still run windows XP most of the time with latest versions of favorite open source applications with little effort, with optimized drivers (unless they buy new hardware).