I wasn't an Atari guy, so my experience with them was only at friend's houses, but that screen looks familiar to me. Is there anywhere else that the shimmery Atari logs wallpaper the screen like that?
I would say that System disk actually makes more sense. TOS as I understand it is the OS. Many users might not know what that means right off the bat. They likely would know what a system disk was as long as they spoke English. After the first boot of a new machine, it would likely not matter anymore what was on the screen, as the user would already know what was meant.
