The Microsoft War on Cost team conducted research to determine the on-going operations and management costs for Hyper-V in comparison with VMware's ESX and vSphere products.
The research intended to answer two questions: which platform is less expensive in IT labor to operate on an on-going basis, and do the systems management products used to manage the environment impact the cost of managing either or both platforms.
The War on Cost team used HANSA/GCR, a market research firm, to deliver a web-based survey to enterprises with 500 PCs or greater and collect the results.
The research results show that customers running Hyper-V spend 24% less on IT labor, on an ongoing basis, than customers using either ESX or vSphere.
Microsoft has published the research white paper title "Hyper v vs VMware ESX and vShpere WP" avilable for download here (PDF).
Here is the Whitepaper in read-only mode: