Drop Down Menu with Image on Hover

Hi All,

I’ve been trying long and hard to get an image appear in the div next to my links on hoover, I’m using the wp_list_pages(); function to get my pages and using css to make drop down menu, i’ve got that far, but how do I add an image to it, here is a mock up to show what i’m trying to achive, any help at all would be greatly appreciated.

Sample Image