both tags go in body section: makes a mouseover on an image have a darker effect, clear 100% opacity: without mouseover image is 75% opacity...


<img style="opacity: 0.75;
                                    filter:alpha(opacity=75);
                                    border: solid 1px #CCCCCC"
                                id="aimg133"
                                name="aimg133"
                                onMouseOver="onimg('133');"
                                onMouseOut="offimg('133');"
                                src="content/images/agents/133.jpg">


<script language="javascript" type="text/javascript">
            function onimg(a){t=document.getElementById("aimg"+a);
            t.style.border="solid 1px #000000";
            t.style.opacity="1";
            t.style.filter="alpha(opacity=100)";}

            function offimg(a){t=document.getElementById("aimg"+a);
            t.style.border="solid 1px #CCCCCC";
            t.style.opacity="0.75";
            t.style.filter="alpha(opacity=75)";}
        </script>