if (document.images) { 

var img1on = new Image();
img1on.src = "menu_01b.png";
var img1off = new Image();
img1off.src = "menu_01.png";


var img2on = new Image();
img2on.src = "menu_02b.png";
var img2off = new Image();
img2off.src = "menu_02.png";


var img3on = new Image();
img3on.src = "menu_03b.png";
var img3off = new Image();
img3off.src = "menu_03.png";


var img4on = new Image();
img4on.src = "menu_04b.png";
var img4off = new Image();
img4off.src = "menu_04.png";

} 


function On(name) { 

if (document.images) { 
document.images[name].src = eval(name + 'on.src'); 
} 

} 


function Off(name) { 

if (document.images) { 
document.images[name].src = eval(name + 'off.src'); 
} 

}