For a market segment Microsoft was said to have won decisively in the mid-1990s, the company spent a lot of time in 2004 putting out fires on the browser front. Like the ghost of the Netscape browser rising to haunt its slayer, Firefox emerged with a vengeance from the Mozilla open-source group, which was founded by Netscape in 1998 and last year spun off by parent company Time Warner. Firefox started off the year a prerelease, name-challenged project by a group that had lost much of its credibility after chronic delays and significant setbacks. But Firefox ended 2004 as a...