Cluster Edition will be Microsoft's first product designed specifically for building data-centre computers based on networks of low-cost servers using clusters.
Microsoft said the software would provide support for server connection standards such as messaging passing interface and remote direct memory access. It also includes an integrated job scheduler and cluster resource management.
Microsoft has already released 64-bit versions of Windows Server 2003, Windows XP and Microsoft SQL Server that support the Itanium processor family, and is developing new versions of the .net framework and SQL Server, or "Yukon", for the Itanium chips.
However, the first release of Windows Server 2003 Compute Cluster Edition will not support Itanium 2.
A Microsoft spokesperson said, "The Compute Cluster Edition is focused on departmental clusters, while Windows Server 2003 for Itanium fulfils the need for customers that require the highest levels of scalability."
Based on Windows Server 2003 Standard Edition, Cluster Edition will instead be optimised for mainstream server chips such as Intel's Xeon and AMD's Opteron, which are 32-bit chips with 64-bit extensions.
Xeon and Opteron are a cheaper option than Itanium and can match it for performance, said Rakesh Kumar, senior vice-president at analyst firm Meta Group.
This suggests Itanium may be moving into the niche mainframe replacement market.
He said the success of Itanium depends largely on Hewlett-Packard and Microsoft. He added that Microsoft's approach was not a full and frank endorsement but a half-hearted statement of selected support rather than a full support of Itanium and Itanium 2.
"Anybody doing any type of work on Itanium needs to consider the future of it, get a lot of qualification from [hardware and software suppliers] and sort out a risk mitigation plan if Itanium does not take off," added Kumar.