1. A method for creating a secure virtualization environment on a host computing device, without modifying the host device, the secure virtualization environment bootable from an external media device, the method comprising: copying, by a client agent executing in a common operating system image stored on the external media device, an operating system of the host computing device to create a copied operating system; comparing, by the client agent, the copied operating system of the host computing device to an operating system stored on an external media device; identifying, by the client agent, unnecessary files and data in the copied operating system of the host computing device; eliminating, by the client agent, the unnecessary files and data from the copied operating system of the host computing device; and creating, by the client agent, an adapted operating system image responsive to eliminating unnecessary files and data.