GREAT SOFTWARE for Testing and Development !!!
Thinstall is an Application Virtualization Platform that enables complex software to be delivered as self-contained EXE files which can run instantly with zero installation from any data source. The core of Thinstall VS is the Virtual Operating System, a small light-weight component which is embedded with each “Thinstalled” application.
Thinstall protects the local PC against changes to the file system and registry for both custom developed and commercial office applications with no source code changes enabling true separation of application and OS.
More info and download: http://www.thinstall.com/