1. A computer program product comprising one or more computer storage media having thereon computer-executable instructions that, when executed by one or more processors of a computing system, cause the computing system to provision a method for provisioning a virtual machine when booted from a generalized virtual machine image, the method comprising: detecting virtual storage media that is accessible to the virtual machine; acquiring a provisioning agent from the detected storage media after detecting the virtual storage media; executing the provisioning agent; acquiring provisioning data from the detected storage media; and using the provisioning data to provision the virtual machine.