The SharePoint capacity planning tools are released.
I like using this as the first step in scoping infrastructure. You'll need to assess the results to see if you think they are sensible.
When you start SCCP you will see the following message;
System Center Capacity Planner is intended to assist the user in designing a deployment topology and selecting the appropriate hardware for the expected user loads. To model the performance characteristics of a given configuration, this software uses configuration and load information provided by the user, combined with hardware-specific capacity and performance information received from other organizations (which Microsoft does not separately verify).
Users should both consult deployment documentation relevant for each technology, and follow standard practices of validating configurations prior to production deployments (such as those described in the Microsoft Operations Framework) because actual configuration performance may vary from predictions due to unanticipated factors such as additional server or network load, inaccuracies in user-provided usage profile characteristics, model errors or other reasons.
Microsoft does not endorse any particular hardware indicated by System Center Capacity Planner.