Highlight an image on mouse over

<script language="JavaScript">
<!--
function HighlightImage(cur,which)
{
strength=(which==0)? 1 : 0.2;

if (cur.style.MozOpacity)
{

cur.style.MozOpacity=strength;

}

else if (cur.filters)

{

cur.filters.alpha.opacity=strength*100;

}

}

// -->

</SCRIPT>