Vhd,ISO,restore files and many other types of files are image files.They are an image of the contents on the hard drive.What makes them different is unknown to me.Some software programs will say that little is known about this or that file type.Are the operating rules that we are seeing for the computer the designer's rules or some system that for some just is.I'm in deep and I am still wondering about the logic system used.With your disk writing software you can make an ISO file that can be used in VBox.If you use a computer restore file you can experiment as much as you want.With VBox you might use XP instead of Win 7.They yell at you for not being x64 even though you are.It's a lot of hard work and then you get stopped somewhere by a pop up.Making a vhd of XP was nice for me.I use it a lot.I put my vhd's on DVD's for future use.