Statistics tracked show that most of the people downloading Firefox 3.0 have so far been Firefox 2.X users upgrading to the latest version rather than converts from competing browsers such as Microsoft's Internet Explorer.
Internet Explorer's market share slipped only slightly from 73.17 per cent at the beginning of June to 72.90 per cent the week of June 22 after Firefox 3.0 was released.
But Internet Explorer has lost significant market share since October 2007, when it owned 79 per cent of the browser market.
How much of Internet Explorer's loss of over six per cent market share over the last ten months can be attributed to Firefox, and how much to Apple's Safari, hasn't been reported yet.