Keep Microsoft's overall importance in software markets in perspective. Microsoft is certainly successful--its $10 billion in annual revenue makes it a leading company. Nevertheless, it accounts for less than 4 percent of total software-industry revenue of $250 billion. And it's not even the largest software company--IBM, with $13 billion in annual software revenue, is tops. Moreover, notwithstanding the prominence of Microsoft's operating systems, it does face competition from numerous vendors, including Apple (Macintosh), IBM (PC-DOS, OS/2, AIX, etc.), Sun Microsystems (Solaris and Java OS), and Digital Equipment Corp. (VMS and Digital UNIX).