If you style an li tag as "display:block" IE 6 and 7 will display the list bullets, whether they are standard markers or images, but Firefox and Safari will not.

Here is an example of the way the list items should look:

The CSS "display" property is set to "list-item" (it could also be left out, since it is the default).

If the display property is changed to block, the list bullets no longer show in Safari or Firefox. However IE 6 and 7 display them.