December 27, 2007: In another effort to defeat Cyber War attacks on their networks, the U.S. Army is expanding the number of Apple computers, particularly servers, that it uses. Currently, only about three percent of the army's 700,000 computers are Apples. But because Apples comprise only about seven percent of all PCs out there, most hacking tools are written for the more commonly found PCs (about 90 percent of the market) running Windows software. Apples are not inherently less vulnerable than Windows PCs, but the hackers have to write special attack software because of the many differences between Apple software (a variant of Unix) and Windows (definitely not Unix). But by mixing up Apples and Windows machines in army installations, another layer of protection is added, making it more difficult for an enemy to get at U.S. military secrets.