If you are like me, almost all of my computers have come with Microsoft Windows. Do you know how many Windows there have been? Years ago I converted from Microsoft MS-DOS to Windows/286. Windows/286 was a far cry from what we have today, but it was a start at desktop computing without having to type complicated or repetitive text commands.
Windows 7 is the new upcoming version, rumored to be released this Fall. I now use Windows XP, Windows Vista, and keep another old computer with Windows 98 SE for old programs and defragging floppy disks. Look here for a history of Windows.
(Update: Windows 7 was released in Nov ’09)