Microsoft VDI Sizing Tool
Microsoft release the Remote Desktop Load Simulation toolset for server capacity planning and perfomance/scalability analysis.
In a server-based computing environment, all application execution and data processing occur on the server. Therefore it is extremely interesting to test the scalability and capacity of servers to determine how many client sessions a server can typically support under a variety of different scenarios. One of the most reliable ways to find out the number or users a server can support for a particular scenario is to log on a large number of users on the server simultaneously. The Remote Desktop Load Simulation tools provide the functionality which makes it possible to generate the required user load on the server.
Detail information and download is in http://www.microsoft.com/downloads/details.aspx?FamilyID=c3f5f040-ab7b-4ec6-9ed3-1698105510ad&displaylang=en