Ref: http://download.microsoft.com/download/1/1/1/11128EC7-2BE7-480C-9D46-4ECECA9E481A/System%20Center%202012%20Licensing%20Datasheet.pdf As I understand it, one System Center license is required for every two virtual servers to be managed, and the terms are far more generous for server-hosted VMs. For example, if you have one big server with 50 VMs accessed remotely, that’s on the low end of pricing ($3,607 retail according to the pricing datasheet above); however, if you have 50 PCs running server OS individually, that’s on the high end of pricing ($33,075 according to the datasheet). Client OS pricing is similar but is done 'per each' rather than 'per two physical CPU', but due to usually having far more clients than servers the price can be much less when contracted. The pricing for Software Assurance and so forth adds to the dynamic. Only a Microsoft licensing specialist can give you the real answer.