Microsoft's share of the browser market has continued to slide, according to a new study, indicating a continued momentum for users switching to Internet Explorer alternatives.

Between the beginning of December and mid-January, Explorer's market share dropped 1.5 percent to 90.3 percent, while the Mozilla Project's Firefox browser rose 0.9 percent to a total of 5.0 percent, according to market researcher WebSideStory. Researchers have shown Explorer's market share falling since June, when WebSideStory had its market share at 95.5 percent.

Other browsers, including Opera and Apple Computer's Mac-only Safari, also gained just under 1.0 percent to 2.1 percent, WebSideStory said.

Figures from OneStat released late last year reflect the same trend, although with different figures. OneStat found that Explorer held roughly 95 percent of the market in May of last year, down to 88.9 percent at the end of November, while Firefox and other Mozilla browsers rose 5.0 percent over the same period to hit a total of 7.4 percent. Both companies track Web user activity from more than 100 countries.

Users and developers have long taken issue with Explorer over frequent security problems and the lack of features that have become standard in the competition, but only in the last six months have users begun to ditch Microsoft's browser in significant numbers.

Firefox still appears to be maintaining the momentum of its highly publicised 1.0 launch ten weeks ago -- the project says users have downloaded more than 19 million copies of the browser. But it could ultimately be stalled at a low figure by factors such as incompatibility with some websites. Enterprises also frequently build in-house applications on the proprietary Microsoft technology supported by Explorer, a factor Microsoft says it is counting on to maintain its dominance. If for nothing else, Explorer is necessary to access Microsoft's Windows Update site.

However, it is ultimately in enterprises' interest to support standards rather that proprietary technology, since every Explorer-centric application increases a business' dependence on Microsoft, according to Francois Bancilhon, chief executive of Linux vendor MandrakeSoft.

"Our customers tell us there are two driving forces behind switching from Windows to Linux: cost, and vendor independence," Bancilhon told Techworld. "Ultimately one of the ways the desktop will evolve from Windows to Linux is by replacing the applications running on top of the operating system. Once customers move to OpenOffice and Mozilla, changing the underlying OS is a no-brainer."