Although Microsoft's Internet Explorer dominates browser market share, Apple's real competition is Firefox, which most active and advanced users love and which is the other major browser not bundled with Windows. Most people inclined to install a second or replacement browser on Windows have already done so, and most have installed Firefox. Firefox fans are small in number compared with Internet Explorer users, but they're a passionate, enthusiastic and vocal crowd. It's these Firefox users that Apple will find at the entrance of the Windows browser market, with swords and shields at the ready.