Microsoft is Apple's "guardian angel", and without its support "Apple likely would have died," according to a report in Wired.
An ex-Apple marketing manager told Wired: "A lot of developers quit the Mac platform, but Microsoft wasn't among them. During the dark days they kept developing Office, and that was way important. That was the true test of loyalty. Others weren't so loyal."
The source suggested that without Office the Mac platform would have withered away: "To have a mainstream platform, you've got to have Office."
Marketing director for Microsoft's Mac business unit Tim McDonough said: "We've been supporting the Mac since its inception. If you look at our history, we were generally there first compared to other (software publishers) on the platform."
Wired noted that with the exception of Microsoft, whose Internet Explorer and Office applications were some of the first programs to be converted to run on OS X, many software makers were "tardy in porting their Mac products to OS X".
Regarding Microsoft's support for the Mac platform, Microsoft's McDonough said: "It's common sense. It's a very good business for us. We have a lot of Mac customers. We have 7 million Office users and there are lots of strategic Microsoft customers who want a cross-platform product for their Macs."
Microsoft has unveiled Office 2004 at Macworld Expo San Francisco.