nav1on = new Image(); 
nav1on.src = "images/nav1_on.gif";
nav1off = new Image(); 
nav1off.src = "images/nav1.gif";

nav2on = new Image(); 
nav2on.src = "images/nav2_on.gif";
nav2off = new Image(); 
nav2off.src = "images/nav2.gif";

nav3on = new Image(); 
nav3on.src = "images/nav3_on.gif";
nav3off = new Image(); 
nav3off.src = "images/nav3.gif";

nav4on = new Image(); 
nav4on.src = "images/nav4_on.gif";
nav4off = new Image(); 
nav4off.src = "images/nav4.gif";

nav5on = new Image(); 
nav5on.src = "images/nav5_on.gif";
nav5off = new Image(); 
nav5off.src = "images/nav5.gif";

nav6on = new Image(); 
nav6on.src = "images/nav6_on.gif";
nav6off = new Image(); 
nav6off.src = "images/nav6.gif";