The new release of Mozilla’s Firefox browser is off to a blazing start—with nearly 10 million downloads as of this writing. That more than doubles the pace of downloads for Microsoft’s Internet Explorer 9, the newest version of the fustiest browser this side of Netscape Navigator. Part of the trick is that Microsoft has opted not to allow the new Explorer to run on Windows XP, its own operating system. The bad news? Firefox 4 is actually behind the pace set by Firefox 3. And there’s worse news: While Explorer’s market share has sunk in the last year, that’s due mostly to growth in the popularity of Google’s Chrome, and Google announced on Wednesday that it’s preparing a beta version of its newest release.