Company revises several features in Vista in response to concerns raised by antitrust officials.
Despite the changes, Vista remains on schedule for worldwide release to corporate customers in November and to consumers in January, Microsoft said on Friday.
Microsoft officials said they now feel comfortable that they have addressed the three main concerns European Commission regulators raised last month.
Last month, the Commission expressed concerns over the search, file-formatting and security features that Microsoft was planning to put into its next-generation operating system. Those matters emerged out of concerns the Commission voiced in March.
"Constructive dialogue followed...and Microsoft has made changes in each of the three areas," said Brad Smith, Microsoft's general counsel. He noted that the Commission provided the clarity the software giant was seeking in order to make the changes. "It's a lot easier to abide by the speed limit when you know what the speed limit is."
As part of the changes, users will be able to select which search service they want to use when upgrading to Internet Explorer 7 from IE 6, Smith said.
The software giant aims to address the controversy surrounding Microsoft's XPS file-formatting capabilities and Adobe Systems' rival PDF by submitting its XPS specifications to a standards body, as well as changing the licensing terms for developers who wish to use the technology, Smith said.
Microsoft also said it would make changes to the way it license the XPS format. The company had already said it would be licensed royalty-free. However, in an effort to make it compatible with open source licenses, such as the General Public License, Microsoft said Thursday that it is also adding an agreement not to sue for intellectual property infringement over the use of XPS.
In another change, Microsoft had planned to lock down its Vista kernel in 64-bit systems, but will now allow other security developers to have access to the kernel via an API extension, Smith said. Additionally, Microsoft will make it possible for security companies to disable certain parts of the Windows Security Center when a third-party security console is installed, the company said.
Security companies had complained that a kernel protection feature called PatchGuard in 64-bit versions of Vista not only locked out hackers but also prevented some security software from running.
Microsoft had maintained that a complete lock on the kernel, a core part of Windows, would provide the best operating-system security and stability. Now Microsoft has committed to providing programming techniques that will enable third-party security products to access the Windows kernel in a secure manner.
Windows Security Center is a key piece of Windows Vista real estate. It tells people the status of security on their Vista PC, such as whether antivirus software or a firewall is installed and running.
The security companies had asked for the ability to replace the operating system's security console with their products. Microsoft had resisted the call but is now giving in, at least in part.
Microsoft will provide a way to ensure that Windows Security Center will not send an alert to a computer user when a competing security console is installed on the PC and is sending the same alert, the company said.
"The commissioner was firm and emphatic that we make these changes," Smith said.
Smith noted, however, that despite these changes, there is no guarantee that the European Commission will ultimately be satisfied with Vista and forgo any antitrust penalties.
Neelie Kroes, the commissioner at the European Union's top antitrust authority, told reporters on Friday that she had spoken to Microsoft Chief Executive Steve Ballmer on Thursday evening.
"He announced that they have intention to ship (Vista) globally," she told reporters on the sidelines of a competition conference in Italy.
After a years-long antitrust case against Microsoft, Kroes warned Microsoft last March that she had concerns about Vista. And in early September, the software company raised the possibility of delaying the launch of Vista in Europe alone on the concerns of the Commission, saying it was unsure what the regulator required of its new product.
The Commission has long said it is up to a company to ensure that its products comply with European Union laws.
"(Ballmer) was aware that he shouldn't ask me if I could give a green light to (Vista), and rightly so," Kroes said of her conversation with the Microsoft executive.
"Microsoft has to be aware that they have a responsibility to take into account the European regulations and European rules, and I am expecting that they are doing that," she said.
The standoff between the software giant and the Commission is the latest in a lengthy spat between the two.
In 2004, the Commission found that Microsoft had abused its market dominance in media players and office servers. It forced the U.S. company to strip out Windows Media Player from its operating system.
The Commission levied a record $624 million (497 million euro) fine at the time. In July, EU regulators fined the company a further $352 million for defying the ruling, which required it to share information on its servers with rivals.
Microsoft faces a further fine of up to $3.8 million a day if found still not in compliance with the ruling.
CNET News.com's Joris Evers and Reuters contributed to this report.