Microsoft Knowledge Base Article 907639 contains the following introduction:

Microsoft Windows Compute Cluster Server 2003 brings together the Windows operating system, the ease-of-use of Active Directory, and the power of x64-based computers to provide an affordable high-performance computing (HPC) solution. Windows Compute Cluster Server 2003 is a cluster of servers that includes a single head node and one or more compute nodes. The head node deploys compute nodes and schedules jobs for the compute cluster. To automatically deploy compute nodes to the cluster, you can install and configure Remote Installation Services (RIS) on the head node. Then, you can stage an image to deploy the compute nodes. RIS has been part of the operating system since the release of Microsoft Windows 2000 Server.