1. A virtual data center implemented on hardware resources of at least one host computer having at least one host processor and system resources including memory divided into most privileged system memory and less privileged user memory, the virtual data center comprising: virtualization software loaded on each host computer, said virtualization software operating in said less privileged user memory and dividing the host computer into a plurality of virtual partitions including at least one user guest partition and at least one system partition, said at least one user guest partition providing a virtualization environment for at least one guest operating system, and said at least one system partition maintaining a resource database for use in managing use of said at least one host processor and said system resources; at least one monitor that operates in said most privileged system memory and maintains guest applications in said at least one guest partition within memory space allocated by said at least one system partition to said at least one guest partition; a context switch between said at least one monitor and said respective guest and system partitions for controlling multitask processing of software in said partitions on said at least one host processor; and a software application that owns a configuration policy for said data center and tracks persistence for respective domains to which each partition of said at least one host computer is assigned by said at least one system partition.