Microsoft on Thursday jumped into the anti-spyware game with the purchase of start-up Giant Company Software in part, according to experts, to save its beleaguered browser from the newest upstart in the market.

Analysts say Microsoft was forced to make a move as it is battered by complaints that its Internet Explorer browser was a portal for spyware’s entrance onto desktops and as it fights public perception that the solution to the problem was Mozilla’s Firefox.

“All the press about Mozilla and Firefox and people getting creamed by spyware and saying if you get off IE you can escape spyware, that meant Microsoft couldn’t wait, they had to come out with something,” says John Pescatore, an analyst with Gartner.

A recent survey by OneStat, which provides Web site analysis software, showed that the market share for IE 6.0 fell to 88.9% in late November, which was down five percentage points from May 2004. Meanwhile, Mozilla browsers, including Firefox, owned 7.4% of the market, up five percentage points since May.

Spyware has become a plague on computer users by slowing down performance and creating avenues for stealing personal data. It is not uncommon to hear of users discovering 50-100 spyware programs on their desktops.

Users are looking for a fix, but for many corporate users that does not include switching browsers because many corporations have built intranet applications using features exclusive to IE. Users says Firefox would have to be made compatible with their applications, which would require a lot of development work not only from corporate developers but from the Mozilla Foundation, which develops Firefox.

In addition to the focus on spyware, Pescatore says Microsoft’s other motivation is that it plans to get into the anti-virus market and tools to fight spyware are now a product feature requirement.

Indeed, anti-virus vendors have been moving to shore up their own wares. McAffee has its AntiSpyware product, CA bought anti-spyware vendor PestPatrol in August and Symantec has said it is adding anti-spyware to its Norton AntiVirus package.

Pescatore says that Gartner predicts Microsoft will come out with a combination anti-virus and anti-spyware product in the second half of next year. In June 2003, Microsoft bought GeCAD, a small anti-virus company, but has yet to develop the technology into a product.