Joe Wilcox said 44 percent of businesses with 250 employees or more allow workers to download Mozilla Corp.'s open-source browser at the office. Last year, only 26 percent of such businesses were willing to do the same.

    "That's a huge jump," said Wilcox. "It's an enormous embrace of Firefox in a very short period of time."

    The increase is probably because of employee demand for Firefox, which can be deployed without disruption to other desktop applications, Wilcox said. It appears workers have found the browser's features, which include the popular tabbed browsing, more useful than the older Internet Explorer 6 from Microsoft Corp.

    Microsoft has remedied that difference with the release out of beta this week of Internet Explorer 7. But few businesses are expected to use the browser upgrade until they install Vista, Microsoft's major Windows upgrade that's set for release to businesses in November.

    The reason for the delay is IE's tight integration with the operating system. Installing IE 7 on a Windows XP machine in an office would require a lot of testing first to determine the impact on business applications. Rather than test twice, companies are more likely to stick with IE6 until Vista, Wilcox said.

    For many businesses, the move to Vista could take a year and a half or more, analysts say.

    As a result, many people who get IE 7 at home through Microsoft's automatic update service will likely find IE6 lacking. Without the option of installing IE 7 at work, they are likely to turn to Firefox, Wilcox said.

    "If you can't have one, then you'll use the other," the analyst said.

    While Firefox is expected to get an up tick in business use, the browser is not expected to overtake IE, which dominates the corporate market. Numbers from Web metrics firms vary, but in October IE had from 82 percent to 86 percent of the market, while Firefox had 11.5 percent to 12.5 percent.

    (Agencies)