Sam Ramji, the director of Microsoft's open-source software lab, posted an open invitation for them to work with the software giant on a Mozilla development discussion group mailing list Monday.
"I'm writing to see if you are open to some 1:1 support in getting Firefox and Thunderbird to run on Vista," Ramji wrote.oversees the development of the open-source Firefox Web browser and Thunderbird e-mail client.
He stressed that Microsoft is "committed to evolving our thinking beyond commercial companies to include open-source projects" fordue for broad release in January.
Ramji was also anxious that Mozilla and the open-source community should not take the offer lightly. He stressed that his contribution to Vista is the "nontrivial effort of getting slots for noncommercial open-source projects."
Early signs from the open-source community indicate that some are suspicious of Microsoft's motives.
But others believe that Monday's offer was a sign that Microsoft is changing. The company has finally realized that "ultimately...proprietary technologies will always get replaced by an industry-supported, open-standard alternative, hence the embrace of RSS, Open Source Lab, XML and royalty-free access to Open XML," one enthusiast wrote in a posting to the Ars Technica Web site.
Firefox already runs successfully on existing Windows, Linux and Macintosh operating systems. Testing by ZDNet UK Reviews found that it also runs well in Vista beta 2, so it's not clear why Mozilla would need help from Microsoft.
Mozilla Europe said it was "too early to comment" on Microsoft's offer.
Colin Barker of ZDNet UK reported from London.