Virtual machine-type-software where you can install other software and test it

Virtual machine-type-software where you can install other software and test it

I remember some software which was like a virtual PC except you didn't need to install an OS, it used the real one. You installed software on it and could use the software in the "virtual PC" and it wouldn't do anything to your "real" computer then if you liked the software you could just transfer it (not reinstall it).