var browserOK = true;
  var pics = new Array();


  var objCount = 0;
  
  function preload(name, first, second){
    if (browserOK){
      pics[objCount] = new Array(3);
      pics[objCount][0] = new Image();      
      pics[objCount][0].src = first;
      pics[objCount][1] = new Image();      
      pics[objCount][1].src = second;      
      pics[objCount][2] = name;            
      objCount++;
    }
  }
  
  function on(name){
    if (browserOK){
      for (i = 0; i < objCount; i++){
        if (document.images[pics[i][2]] != null)
          if (name != pics[i][2]){
            document.images[pics[i][2]].src = pics[i][0].src;
          } else {
            document.images[pics[i][2]].src = pics[i][1].src;
          }
      }
    }    
  }
  
  function off(){
    if (browserOK){  
      for (i = 0; i < objCount; i++){
        if (document.images[pics[i][2]] != null)
           document.images[pics[i][2]].src = pics[i][0].src;
      }
    }
  }
  
  preload("home", "images/btn_home_down.jpg", "images/btn_home_up.jpg");
  preload("download", "images/btn_download_down.jpg", "images/btn_download_up.jpg");
  preload("registration", "images/btn_registration_down.jpg", "images/btn_registration_up.jpg");
  preload("contacts", "images/btn_contacts_down.jpg", "images/btn_contacts_up.jpg");