off the top of my head, i've read that IE8 ignores the *html hack.. not verified but worth a check. Also from your css, the code:
*html #searchPanel .kyefield
background-position: left 0px;
padding: 10px 0 0 15px;
when you add a top padding but keep your height at 40, the new height will be 50px, so that may cause a problem.
What are the differences in IE8 versus FF?