If I install virtual box and install Windows within it as one virtual machine. Can viruses or other malware / trojans -- whatever you want to call it -- infect the host machine (imac)? Or can the virtual Windows install get totally effed up beyond all recognition and when I close Virtual box everything goes away? Is it better to actually delete that virtual machine periodically? I guess my question is just how compartmentalized is the Virtual Box environment? Completely, mostly, sort of?