Microsoft. who reacted to the growing threat of Firefox by hurrying the release of Internet Explorer 7.0, has expanded the number of platforms for the new browser. However, although the browser will run on Windows XP with Service Pack 2, Windows Server 2003 with Service Pack 1 and Windows XP Professional x64 Edition, the company is not making the browser available for Windows 2000

IE 7.0 was originally planned to be included in Longhorn but Microsoft said it changed its plans due to customer demand. Microsoft chairman Bill Gates announced the imminent arrival of IE 7.0 at the RSA Conference two weeks ago, although, apart from mentioning the enhanced security features, he was sketchy about details.

Now, more details on IE 7 are trickling out as Microsoft works on the browser upgrade. Late on Monday, the IE team at Microsoft wrote on its weblog that the browser would be available for "Windows XP SP2 and later," which also includes the forthcoming Windows Server 2003 SP1 and Windows XP Professional x64 Edition, according to the weblog.

However, corporate users who have yet to upgrade to Windows XP, would also like to see a version of IE 7 for Windows 2000. Microsoft has heard those requests, but has nothing to announce at this time, according to the log.

Since the IE 7 announcement, Microsoft also has fielded questions about a possible new version of Outlook Express, the free e-mail client that was bundled with IE in the past. Outlook Express is "not part of the IE7 plan," according to the Web log. A new version of Outlook Express is set to ship with the next release of Windows, the IE team wrote.

IE is part of Windows and is used by most Web users, but it has a reputation for poor security. Other browsers such as Firefox, Netscape and Deepnet Explorer are exploiting that reputation. IE's share of the browser market has dipped below 90 percent, according to a recent survey.