I am trying to create an image that will swap to an alternative while still be able to be used to be linked to another page.

I have created the image in the mouse-off state and the alternative in the mouse over state and the only way so far I have managed to find to get them to swap is to create a new page and then link to this. For what I am trying to do I would then not be able to link to another certain page on the site.

Is there something else that I am missing to get this to work?