Microsoft chairman Bill Gates said IE 7.0 will debut before Longhorn. At the RSA Conference in San Francisco, Gates acknowledged that IE had become a security risk and promised a beta of IE7 will be available this summer for Windows XP SP2.

The update will include new anti-spyware features, and likely draw on Microsoft's recent acquisitions of security companies GIANT and Sybari.

Microsoft executives had previously held firm that Longhorn -- due in 2006 -- would bring the next major changes to Internet Explorer. In the past few months, however, Redmond has faced increased security threats and an eroding market share following the launch of Mozilla Firefox.

Microsoft's Internet Explorer Web log shed some additional light on the decision to separate IE from Windows.

"Why? Because we listened to customers, analysts, and business partners. We heard a clear message: 'Yes, XP SP2 makes the situation better. We want more, sooner. We want security on top of the compatibility and extensibility IE gives us, and we want it on XP. Microsoft, show us your commitment.'," wrote IE team head Dean Hachamovitch.

Microsoft officials have not ruled out an IE7 release for Windows 2000, but say the current plan only involves Windows XP Service Pack 2.

"Right now, we're focused on XP SP2," said Hachamovitch. "We're actively listening to our major Windows 2000 customers about what they want and comparing that to the engineering and logistical complexity of that work. That?s all I can say on that topic."