if (document.images) { 

var img1on = new Image();
img1on.src = "images/navi_header_home_on.gif"; 
var img1off = new Image();
img1off.src = "images/navi_header_home.gif";

var img2on = new Image();
img2on.src = "images/navi_header_sitemap_on.gif";
var img2off = new Image();
img2off.src = "images/navi_header_sitemap.gif";

var img3on = new Image();
img3on.src = "images/btn_top01_on.gif";
var img3off = new Image();
img3off.src = "images/btn_top01.gif";

var img4on = new Image();
img4on.src = "images/btn_top02_on.gif";
var img4off = new Image();
img4off.src = "images/btn_top02.gif";

var img5on = new Image();
img5on.src = "images/btn_top03_on.gif";
var img5off = new Image();
img5off.src = "images/btn_top03.gif";

var img6on = new Image();
img6on.src = "images/btn_top04_on.gif";
var img6off = new Image();
img6off.src = "images/btn_top04.gif";

var img7on = new Image();
img7on.src = "images/btn_top05_on.gif";
var img7off = new Image();
img7off.src = "images/btn_top05.gif";

var img8on = new Image();
img8on.src = "images/btn_top06_on.gif";
var img8off = new Image();
img8off.src = "images/btn_top06.gif";

} 


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'); 
} 

}