Not even the search giant Google and its new Google Chrome can steal the browser market from Microsoft.
Lesser competitors have struggled to get people to download software to replace Internet Explorer, which has been the laggard in browser performance for years. Most people don't want the hassle or fear the unknown. Internet Explorer is already on all Windows computers and works well enough. It's a safe choice. It's secure enough, easy enough to use, and most sites work with it.
Mozilla's Firefox, a browser called Opera, and Apple's Safari have kept ahead of Internet Explorer with features and/or speed. But we're creatures of habit, and the competitors haven't had the name recognition and marketing savvy to sell their alternatives.
Google has the dollars, a well-known name, and marketing wits. It might make headway. But judging from a new version of Internet Explorer that was released for testing, Microsoft can keep pace. The default choice for Windows users will be good enough.
The only thing that will unseat Internet Explorer is an unseating of Windows. And despite Vista's problems, that's not happening anytime soon.