The HP Sizer for Microsoft Hyper-V 2008 R2 is an automated, downloadable tool that provides quick and helpful sizing guidance for “best-fit” HP server and storage configurations running in a Hyper-V R2 environment.

The tool is intended to assist with the planning of a Hyper-V R2 virtual server deployment project. It enables the user to quickly compare different solution configurations and produces a customizable server and storage solution complete with a detail Bill of Materials (BOM) that includes part numbers and prices. The HP Sizer for Microsoft Hyper-V 2008 R2 allows users to create new solutions, open already existing solutions, or use other types of performance data collecting tools, such as the Microsoft Assessment and Planning tool (MAP), to build rich Hyper-V R2 configurations based on HP server and storage technology. The tool allows rapid comparison of Hyper-V R2 characterizations using various HP server and storage choices. 

Source: http://h71019.www7.hp.com/ActiveAnswers/us/en/sizers/microsoft-hyper-v2008.html