As my computer kept urging me to back up my system onto an external hard drive, I decided I would buy one, but first I needed to find out which size to buy; so I backed up the system on the computer itself to find out how much space it takes up. This created two files (one, WindowsImage, and another one which shows an icon of a disc.) However, when I click on the icons and then on "Properties", it tells me that there are 0 bytes in the file: which is of course nonsense, since the file ("New Volume (F:)") into which I stored them shows over 60 GB being taken up. So, two questions: why the "0"s? And will it damage anything if I delete these two files?