HPC Pack 2008 R2 is the high performance computing component of Windows HPC Server 2008 R2. It includes management tools, a job scheduler, and Microsoft Message Passing Interface (MS-MPI), and the client utilities. The Enterprise and Workstation editions additionally includes HPC Services for Excel and the ability to join workstation nodes to the cluster.

Licensing
If you are using the Microsoft HPC Pack with a different edition of Windows you will need to comply with the licensing programs for that edition of Windows.

HPC Pack can be purchased separately or combined as Windows HPC Server 2008 R2

This license comes with Microsoft's Maintenance Program, Software Assurance (SA).