if (document.images){
	nav_prev_on = new Image();
	nav_prev_on.src="img/nav/prior3_b_on.gif";
	nav_prev_off = new Image();
	nav_prev_off.src="img/nav/prior3_b.gif";

	nav_top_on = new Image();
	nav_top_on.src="img/nav/top3_b_on.gif";
	nav_top_off = new Image();
	nav_top_off.src="img/nav/top3_b.gif";

	nav_next_on = new Image();
	nav_next_on.src="img/nav/next3_b_on.gif";
	nav_next_off = new Image();
	nav_next_off.src="img/nav/next3_b.gif";
}
function imgOn (imgName){
  if(document.images){
        document[imgName].src=eval(imgName + "_on.src");
        }
}
function imgOff (imgName){
  if(document.images){
        document[imgName].src=eval(imgName +"_off.src");
        }
}