Windows Server 2003 is available for X86, X64 and Itanium platforms. SQL Server 2005 is available for Windows Server 2003 for 32-bit architecture, Windows Server 2003 for 64-bit architecture and Windows Server 2003 for Itanium. Clustering is greatly developed in Windows Server 2003.
Windows Server 2003 comes in a variety of editions, including
* Standard Edition
* Enterprise edition
* Datacenter Edition
The edition of window server 2003 that you choose depends upon number of required CPUs and amount of memory required. It is possible to use SQL Server 2005 32-bit on windows server 2003 64-bit, but you can not use SQL Server 2005 64-bit on windows server 2003 32-bit obviously.
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