Jordan Chrysafidis, director of Windows server systems at Microsoft Canada, said NT 4 was the company's first enterprise server product that had real resonance with customers.

"It really was the first watershed operating system that Microsoft shipped that had mass adoption. . . . When customers are making mass choices like that, you really do need to work with them in terms of doing the upgrade," he said.

Gordon Haff, senior analyst with Illuminata, agreed that NT 4 was a turning point and Microsoft's "first solid beach head into being a real enterprise server OS."

For that reason, some customers may be reluctant to part with NT 4. "There's nothing really wrong with NT, especially if you've been at it for a while and had all your scripts written and your set-up done," said Brad Biehn, director of IT for Louis Riel School District in Winnipeg.

But Biehn felt compelled to move his organization over to Server 2003 earlier this year, and is actually considered one of that operating system's early adopters. "There's still some people trying to run Windows 95 or Windows 98. You can't run stuff forever," he said. "We couldn't wait any longer. I wish we could have."

For customers still on NT, Microsoft is providing online migration support via Microsoft.com/upgradeNT. For those who cannot part with NT, the fee-based support program will be available until the end of 2006. Chrysafidis said pricing for program will be arranged for the service on customer by customer basis, but doesn't expect a huge demand for it. "I can say with confidence, it's less than a dozen companies in Canada."

Microsoft has indulged its customer base by keeping support for the product around for a decade, but extensions may actually do more harm than good.

"I think it became clear that if the deadline was infinitely movable, then it really wasn't a deadline," said IDC's Dan Kuznetsky. Users could leverage their NT investment almost indefinitely, in spite of the presence of superior products.

"Because they've been so unsure as far as where they've decided to draw the line, customers can never tell whether they're serious," said Rob Enderle, principal with the Enderle Group. "The problem Microsoft has is they've set in place a policy of how they're going to retire this stuff, then they continue to change this policy.

"They're really not doing anyone any favours here, least of all themselves. To their credit, they're trying to do the right thing (but) they're actually creating a bigger mess for themselves."

Few vendors will support the products that they originally created to run on NT 4, said Kuznetsky. And the number of security threats facing NT 4 are probably more than Microsoft can realistically deal with, said Haff.

"Because of certain underlying code structure and, frankly, the somewhat haphazard nature of the NT code base, it really isn't possible for Microsoft to make NT 4 secure in any real way. Even making their best efforts is really a losing battle there," he said.

In some regards, NT 4 has been a victim of its own success, but Chrysafidis said the on-again, off-again support situation with the operating system is unique. "I don't think it's going to be the same kind of issue going forward," he said, "just because NT 4 was a learning experience -- not just for our customer base but also Microsoft in some respects."

Microsoft has announced plans to retire support for Exchange Server 5.5, which will follow the NT 4 model: extended support will end on Dec. 31, 2005 with two years of fee-based support to follow.