The servers, previously known by the codename "Whistler" and then by the temporary name of Windows 2002 servers, are the follow-on to the Windows 2000 servers released about 18 months ago. (Windows 2000 Datacenter Server shipped six months after the general Windows 2000 launch).

The Windows .NET Servers primarily retain the core enhancements of the prior Windows 2000 generation of servers and have been nicknamed Windows NT Server 5.1 by some industry observers.

Core enhancements across all four versions of the server are the inclusion of the .NET Framework, the inclusion of ASP.NET technology and an upgrade to version 6.0 of Internet Information Services (IIS).

Analyst John Enck of Gartner contends that Microsoft has obstacles to pushing the .NET Server upgrade on the enterprise.

"Microsoft continues to struggle with positioning .NET Server versus 2000 and pushing on this issue of what is the differentiation between these two products?" Enck says.

Reverting to the "Enterprise" name for the mid-range server resumes a pattern in Microsoft's efforts to brand its premium version of the core server operating system. In the Windows NT 3.5 generation, Microsoft had an Advanced Server. In 1997, Microsoft supplemented Windows NT 4.0 with an "Enterprise Edition." By 1998, Microsoft had decided to reuse the "Advanced" name for Windows 2000 Advanced Server. Now, it's back to "Enterprise."

This time, Microsoft is representing its "Enterprise" version as the standard server product for bigger customers.

In the .NET Server generation, Standard Server will support no more than two processors, won't be available in a 64-bit version, won't include Services for Macintosh and won't support Metadirectory Services. Customers who would have used Windows 2000 Server on three- or four-processor machines would need to move to Windows .NET Enterprise Server if they wanted to upgrade.

"It's very much reminiscent of the way they were shifting things around in the Windows 2000 release," notes Dwight Davis, an analyst with Summit Strategies. During the development cycle of Windows 2000, Microsoft tried to limit the number of processors supported in Windows 2000 Server.

If the pricing of Windows 2000 servers is any guide, the Advanced Servers sold for about three times as much money as regular Windows 2000 Servers -- an estimated retail price of $3,999 with 25 CALs for Advanced Server versus $1,199 with 10 CALs for Server.

Although Microsoft has a financial incentive to get corporate users to accept the change, Gartner's Enck believes Microsoft is following customers' lead.

"I think the reality is that most of the serious corporate guys were deploying Advanced Server anyway. I think the trend that was established through Windows 2000 with Advanced Server by default was sort of the corporate mainstream server," Enck says.