In the tiny, cramped dressing room named for Jerry Garcia in the bowels of San Francisco's Warfield Theatre, Microsoft Corp. President and CEO Steve Ballmer looks like the proverbial caged lion. At Microsoft's Enterprise Server 2000 launch event in September, Ballmer positively roared that the software giant, which enjoys a desktop monopoly so vast a federal judge branded it illegal, is ready to ride Windows into the heart of the enterprise.