Hewlett-Packard Co has finally kicked the mainframe habit, and on Friday claimed that it is now the largest company in the world running its mission-critical applications exclusively on distributed open systems over the world’s largest Intranet. During a midday celebration in honor of the event, Lewis Platt performed a ceremonial unplugging of the water-cooled, monolithic machine in the Palo Alto data center and left the entire company to the tender mercies of the Intranet environment of 84,000 personal computers running the same core software applications. 23,000 desktop Unix systems; 6,000 servers; 1,600 Web servers; and the Netscape Communications Corp Navigator running on 60,000 desktops.