WASHINGTON A U.S. appeals court ruled unanimously in favor of Microsoft Corporation Tuesday by determining that its Windows 98 is not covered by a lower court's injunction blocking distribution of an earlier version of the computer operating system. The December injunction backed the U.S. Justice Department by ordering that Microsoft could not require computer makers to take Microsoft's Internet Explorer software as a condition of licensing the Windows 95 system, which controls about 90 percent of the world's desktop computers. Microsoft plans to begin shipping Windows 98 on Friday. The Justice Department had sought to block its release, arguing that the December injunction also covered the updated version of Windows. The Justice Department argues that Microsoft is trying to extend its virtual monopoly over operating systems to the Internet by packaging Explorer inside Windows. The company argues that restricting its marketing would stifle innovation in the competitive computer software market. (DPA)