CNET News.com details its observations on Mozilla Firefox browser gaining in popularity. W3Schools.com, a Web development tutorial site found that Mozilla-based browsers were used by 18% of its visitors in September, up from 8% in January. MSIE use dropped to 75% from 84%. Among CNET News.com readers, site visitors with the Firefox and Mozilla browsers jumped to 18% for the first two weeks of September, up from 8% in January 2004. Downloads of the Firefox browser have doubled from 3 mln for version 0.8 to 6 mln for version 0.9. Web analytics company WebSideStory says Mozilla-based browsers' market share grew to 5.2% in September, from 3.5% in June 2004. Meanwhile, Microsoft's share of the users shrank from 95.5% in June to 93.7% in September, according to the company.