I would like to know what happens when I substitute an album cover. Let's say I have a crappy cover from Amazon (downloaded thru OCD) and later I find a really nice one.

I take this new, shiny album cover and replaces the old one with this one. What happens to the old album cover? Is it still in my graphics folder?

If so, it would be nice to be able to remove all album covers that's not in use.