Modifying the bullets

Guys, just something simple (probably for you anyway). I have done this before but cant remember how I did it.

How do I add an image beside each of the links in a list. I am not sure whether to change the bullet sytle or just add an image beside the text.

Basicaly, my list is set inline as a horrizontal nav bar styled just with css. I want to add a small bullet-style image to the left of each entry which I can then also have control over using css (set border, margins etc)

I think I did this by editing some of the core files but I cant reember which one(s) and also if possible I want to do it this time using the template files if possible.

Can someone help/advise on this please.

F