//rollover function for navigation
function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}
<!-- For rollovers
image1= new Image( );
image1.src="images/navImages/why_ON.jpg";
image2= new Image( );
image2.src="images/navImages/why_OFF.jpg";

image3= new Image( );
image3.src="images/navImages/experience_ON.jpg";
image4= new Image( );
image4.src="images/navImages/experience_OFF.jpg";

image5= new Image( );
image5.src="images/navImages/research_ON.jpg";
image6= new Image( );
image6.src="images/navImages/research_OFF.jpg";

image7= new Image( );
image7.src="images/navImages/compliancy_ON.jpg";
image8= new Image( );
image8.src="images/navImages/compliancy_OFF.jpg";

image7= new Image( );
image7.src="images/navImages/awards_ON.jpg";
image8= new Image( );
image8.src="images/navImages/awards_OFF.jpg";