Challenger: Dell Services

Last year, Dell Services became NTT Data Services after the Japan-based firm acquired Dell's former services arm. In North America, the company provides services through 506 agents in the U.S. and another 1,452 in Europe, India, Mexico, Central America and Malaysia, according to Gartner. The company provides on-site desktop services through about 2,400 desktop technicians. In North America, Dell Services supports approximately 3.9 million service desk users, 1.4 million desktop users, more than 1.2 million physical desktops/laptops and 977,000 mobile devices. Approximately 14,200 users are serviced through walk-up kiosks, according to Gartner.