Windows Server 2008 R2 Datacenter is optimized for large-scale virtualization on small to large server systems and for workloads that require the highest levels of scalability, reliability, and availability to support large, mission-critical applications.
With unlimited virtualization use rights and a hyper visor-based virtualization technology, Windows Server 2008 R2 Datacenter provides the flexibility and cost savings to easily run large numbers of virtualized Windows Server instances.
Server virtualization technology lets you optimize system utilization and resources and realize significant infrastructure and management cost savings. Windows Server 2008 R2 Datacenter provides an ideal platform for enterprise-scale virtualization. Windows Server 2008 R2 Datacenter features Hyper-V, a flexible high-performance hyper visor-based virtualization technology. In addition, Windows Server 2008 R2 Datacenter licenses include unlimited virtualization rights, meaning that you have rights to run an unlimited number of Windows Server instances on servers licensed with Windows Server 2008 R2 Datacenter.
Microsoft Windows Server 2008 R2 Datacenter - licence
Microsoft Windows Server 2008 R2 Datacenter - BIOS-locked (IBM)