After nearly five years of living in technological harmony, Apple and Microsoft are due to renew their vows.

In August, a contract forged in 1997 between Microsoft and Apple expires, leaving both companies legally unchained. Both corporations this week declined to comment on whether they plan to renew the contract. However, analysts and company officials said that technical cooperation, such as the development of Microsoft’s Office software for Macs, will continue. Roger Kay, director of client computing with IDC, said: “Office for Mac is a really integral part of what Apple is offering. It’s critical for Apple to have the Office suite”.

Microsoft has scheduled a presentation for April 10 at its Mountain View, California, campus where Kevin Browne, general manager of Microsoft’s Macintosh Business Unit (MacBU), is expected to discuss the future of the group and its products now that the contract is nearing its end.

Apple must not slip through the .Net Analysts said maintaining ties will also be important for Microsoft as it pursues its .Net initiative for delivering software and services over the Internet.

Some of Wednesday’s presentation will touch on .Net’s role in the Mac community, Microsoft said. It comes as Microsoft pushes to get developers and users to adopt its .Net products.

“It’s critical to Apple that they get this .Net blessing, otherwise they’re going to get forced out of the corporate network,” said Rob Enderle, research fellow with Giga Information Group. Enderle noted that many Giga customers have raised concerns recently about the cost and difficulty of supporting Macs within corporate networks.

While Microsoft confirmed Tuesday that it plans to bring Apple into its .Net to some degree, Apple has been vague about how it will support the technology.

One piece of technology that would bridge Apple’s Macintosh operating system with .Net is already in the works, though not at Apple. Microsoft and Corel have developed an alternative version of the .Net runtime environment, known as the .Net Framework, for the FreeBSD operating system. FreeBSD is a variant of Unix and is also at the core of OS X.

Cross-platform networking Bringing Apple into Microsoft’s .Net plans could also improve networking compatibilities between Mac and Windows systems, Enderle noted.

Apple has promoted its operating system since OS 9 as being Windows-friendly. Sharing files between Windows and Mac machines is seamless, said Al Gillen, research director of software systems at IDC. Even so, Mac clients are still sore thumbs in corporate networks that use Microsoft server and database software, Enderle said.

One issue is Unix implementation in OS X. “This Unix component is working against them,” Enderle said. “The OS is basically Unix with an Apple front end, but from the administrators’ point of view, all they see is Unix.” Gillen also cast doubts on whether organizations will be prepared to manage large blocks of Unix clients.

Additional work on behalf of Microsoft and Apple could iron out any issues that keep Windows and Mac users apart, Enderle said. One way to do that would be for Apple to come up with a strategy that allowed its users to use Microsoft’s .Net services.