Q: When running the Microsoft Assessment and Planning Toolkit against my Windows 2003 servers, it's not correctly reporting the number of physical processors in the machine--why?

A: Many organizations still have a large number of Windows 2003 and Windows XP machines in their environment. To help with the migration planning to Windows Server 2012 and Windows 8, organizations use the Microsoft Assessment and Planning Toolkit to get a good idea of their existing environment and also to understand licensing needs.

Windows 2003 and Windows XP machines sometimes incorrectly report the number of processors they have, which might cause organizations to believe they need more licenses than they really do (since Windows Server 2012 is licensed by physical processor).

The problem is caused by servers that have processors with multiple cores or that have hyper-threading. Windows 2003 and Windows XP don't have the functionality to detect and report on processors with multiple cores or that have hyperthreading enabled and therefore confuse these features as separate physical processors.

To get the correct information, it is necessary to install a hotfix on Windows 2003 systems that adds the required information to WMI via the Win32_ComputerSystem and Win32_Processor classes.

For Windows XP systems, this XP hotfix must be installed.