In one aspect, a method of creating a virtualized computer environment that represents a real world computer environment is provided. The real world computer environment comprises a plurality of components, the plurality of components comprising a plurality of computer devices and at least one network device that implements a network that interconnects the plurality of computer devices, the real world computer environment comprising at least one security facility that implements at least one security function in the real world computer environment. The method comprises acts of including in the virtualized computer environment a virtualized representation of at least one of the plurality of computer devices in the real world computer environment and implementing the at least one security function in the virtualized computer environment. In another aspect, a virtualized representation of the at least one network device is provided. In another aspect, software is executed in the virtual computer environment.