if(document.images)
 {
  p1 =  new Image();
  p2 =  new Image();
  p3 =  new Image();
  p4 =  new Image();
  p5 =  new Image();
 
       
  p1.src = "graphics/index_over_11.gif";
  p2.src = "graphics/index_over_12.gif";
  p3.src = "graphics/index_over_13.gif";
  p4.src = "graphics/index_over_14.gif";
  p5.src = "graphics/index_over_15.gif";
  
 }