Vista's failure is mostly because the graphics driver couldn't be stable on time, thus, there is no point to switch for gamers. Fixed as time goes on. And now Vista has stable graphics drivers, which works on Win7.
Another failure is that Vista is not eye candy enough. Same old taskbar, paint, and an useless Mail application. Live Mail is way better and it works on XP. No advantage over XP. Same WMP, same IE, same Photo Gallery, same Media Center. Added with bothersome
security control. Win 7 didn't really fix some of the problem, but at least the taskbar is new and you can do touch stuff.
Anyway, future of Windows? I thought it would be Singularity, Surface, Live Mesh, and other stuff.