if (document.images)
   {
     image_off= new Image(550,200);
     image_off.src="bsd08-top_550x200.gif";  

     image1= new Image(550,200);
     image1.src="bsd08-top_550x200.gif";
	 image2= new Image(550,200);
     image2.src="bsd08-top_550x200_introduction.gif";
	 image3= new Image(550,200);
     image3.src="bsd08-top_550x200_program.gif";
   }

function change1(picName,imgName)
 {
   if (document.images)
    {
      imgOn=eval(imgName + ".src");
      document[picName].src= imgOn;
    }
 }