The best OS in the world ?
Windows 7, something truly exciting. From the same man who wrote Groove, Ray Ozzie, and designed on the same philosophy, keep it simple, and don't ask the user to do your job of setting up and finding drivers and a whole lot of other exasperation that drove people to the Mac.
And believe it or not, it runs even on a Pentium III, amazing, total redesign of the OS not the incremental stuff that MS has been inflicting (Vista) on us for years
way to go MS - you may just become a well loved company again some day soon :-)