ComputerWorld reports that Microsoft's share of the operating system marketplace continues to shrink, and has now fallen below 90% for the first time in more than a decade. The recent 2% drop in marketshare was made up primarily by Apple, and a much smaller gain in Linux-based computers. Microsoft's share of Web browsers has also been shrinking steadily, with FireFox, the free open source browser, taking most of the users away from Internet Explorer. Safari, the Mac Web browser, has also made smaller gains.