At Microsoft’s official launch in NY of Windows 8, CEO Steve Ballmer projected that 670 million PCs will upgrade to the new software. Windows 8, which goes on sale Friday, allows users to write on the screen with fingers or a stylus. Lenovo, Dell, Acer, Toshiba, Sony, Asus and HP presented their new Windows 8-compatible PCs. They are completely redesigned to convert into tablets with touchscreens. Ballmer called them the fastest, thinnest, lightest and best PCs ever created—and will usher Microsoft and its customers into a new era.