In its latest step to comply with its still-pending federal antitrust settlement, Microsoft Monday readied the release of Windows XP Service Pack 1 (SP1), which will give computer makers and consumers the ability to avoid five key Microsoft middleware programs.

SP1 is designed to answer the charges that Microsoft unfairly favors its programs over those from rivals. The service pack will give computer makers and consumers the ability to avoid Microsoft five middleware programs: Internet Explorer, Outlook Express, MSN Messenger, Windows Media Player, and Microsoft's Java Virtual Machine. For example, it will include on Windows a new start menu button called "set program access and defaults" that allows users four choices: computer-maker's settings; Microsoft only; non-Microsoft only; and customized. The default choice is customized.

Microsoft released a similar service pack for Windows 2000 in early August. SP1 will be available for free on the Web or for $9.95 on CD.

The release of SP1, announced in late May and released in beta in June, follows up on Microsoft's disclosure last month of 272 application protocol interfaces.

Both moves, in addition to a program for licensing 113 Windows communication protocols begun earlier this summer, were required in Microsoft's antitrust settlement last fall with the Justice Department and most of the states suing the company. The settlement is pending, while U.S. District Court Judge Colleen Kollar-Kotelly decides an antitrust case pursued by nine states that rejected the settlement as too lenient. Her ruling is expected sometime this fall.

The service pack could prove a boost to computer makers and users frustrated by Microsoft's stranglehold on the desktop through its ubiquitous Windows operating system. The new options could help computer manufacturers, who can now choose third-party middleware, as well as rival manufacturers of Microsoft products like AOL Time Warner and RealNetworks.

In addition to the mandated middleware changes, SP1 includes patches for hundreds of bugs found since XP was released in October 2001. Microsoft Chairman Bill Gates has pushed the company to be more conscientious of security flaws as part of the "Trustworthy Computing Initiative" he began in January.

The most high-profile result of the push was the announcement early this summer of Palladium, Microsoft's far-reaching effort to secure computers that critics have painted as another Microsoft plot to control computer users' choices.

Despite the Gates decree, Microsoft's products have continued to be dogged by security flaws. Just last Thursday, Microsoft released critical patches for flaws in most of its Windows platforms that can leave the systems susceptible to identity spoofing. Meanwhile, a security advisory firm today issued its tenth security warning for a vulnerability in Microsoft's Internet Explorer browser.

Microsoft's moves to comply with the still-pending settlement could be washed away in Judge Kollar-Kotelly's ruling. The states still suing Microsoft want more widespread remedies, including Microsoft publishing its entire Windows source code. Microsoft has refused to consider a compromise that goes further than its settlement with the Justice Department.