Microsoft is working hard on the successor to Windows 7, and version 8 will be radically different. Windows 7 was designed for desktops and laptops, but the new version revolves completely around tablets and mobile devices. It will take a lot of getting used to. But you can already safely work with the new operating system without needing to completely reinstall everything on your PC.
Microsoft isn't known for being a company that likes drastic changes. The way we use Windows now goes all the way back to Windows NT 3.1 that came out in 1993. At that time Microsoft introduced the taskbar and start menu, features that we 19 years later are still using in more or less the same form. It's an interface that works great with mouse and keyboard, but not at all practical for a touch screen device. The icons and other elements are just too small.
Windows 8 breaks the mold with Metro
No more start menu to access your programs
Via Charmes on the sides of the screen you can access commands in Windows 8.