Although Microsoft recently touted the 100 millionth installation of Internet Explorer 7, Web measurement firms said that the new browser is simply being swapped out for older editions and hasn’t had an impact on Firefox’s continued climb. “[As of] January 8th, we had the 100 millionth IE7 installation,” said Tony Chor, an IE group program manager, in an entry on the team’s blog. “Even more important than installations is usage. According to WebSideStory (the company we use to measure browser usage), as of this week, over 25% of all visitors to sites in the U.S. were using IE7, making IE7 the second most used browser after IE6.” While Microsoft had the WebSideStory numbers correct, it didn’t tell the whole story, says Geoff Johnston, an analyst with the Web metrics company. “[The growth of IE 7] seems to be exclusively at the expense of IE 6,” says Johnston.