1. A method, comprising: (a) providing a host operating system; (b) obtaining an integrity metric for the host operating system, wherein obtaining the integrity metric includes performing a hash function to all or selected data files associated with the host operating system; (c) running a plurality of virtual machine applications on the host operating system; (d) running a guest operating system in each of the virtual machine applications; and (e) obtaining an integrity metric for each of the virtual machine applications.