Microsoft System Center is Microsoft’s centralized management platform for just about every Microsoft enterprise function (“from data center to desktop”, as Microsoft says).
More specifically, Microsoft System Center Virtual Machine Manager is the centralized management platform for virtualization. Microsoft calls it their “comprehensive virtualization management tool”. It can perform virtual machine monitoring, configuration, provisioning, and administration. The latest version, VMM 2008, can manage Microsoft Hyper-V, Virtual Server 2005, and VMware ESX Server platforms.
Image Source: Microsoft.com