I just doubled checked, if you do not specify a src attribute, firefox 2 uses a default alt value.
When you say not compatible, are you mainly referring to positions and/or hover? If hover, see below
That's the part that I've been having some problems with. See updated example http://evoluent.bugeyedigital.com/ I originally tried using an image for the src attribute for the view cart button, mainly wanting to get the hover effect, but ran into some issues. So I removed the src completely and used background-image instead to get the hover effect, but IE insist on displaying that icon when src is not set, so for now on the view cart button, worked around the IE problem by including a tiny transparent image for the src to get rid of the icon while keeping the background-image in the css. Hover effect does not work in IE6, but works fine with firefox. Look wise, fine on both now.
Now trying to figure out how to line up the add to cart buttons correctly with the 3 corresponding inline list buttons to the left of each.
What's is up with IE, all versions up to 8 ? I checked the rendering on browsershots.org, practically all versions of different browsers look fine, EXCEPT for all IE.