if (document.images)
{
  pic1= new Image; 
  pic1.src="images/menu/menu_1.gif"; 
  pic1.src="images/menu/menu_1_over.gif"; 

  pic2= new Image; 
  pic2.src="images/menu/menu_2.gif"; 
  pic2.src="images/menu/menu_2_over.gif";
  
  pic3= new Image; 
  pic3.src="images/menu/menu_3.gif"; 
  pic3.src="images/menu/menu_3_over.gif";
 
  pic4= new Image; 
  pic4.src="images/menu/menu_4.gif"; 
  pic4.src="images/menu/menu_4_over.gif";
  
}