if (document.images) {

 bestbtobon = new Image();
 bestbtobon.src = "/images/menu_bestbtob_on.gif";

 bestbtoboff = new Image();
 bestbtoboff.src = "/images/menu_bestbtob_off.gif";

 advertisingon = new Image();
 advertisingon.src = "/images/menu_advertising_on.gif";

 advertisingoff = new Image();
 advertisingoff.src = "/images/menu_advertising_off.gif";

 contactuson = new Image();
 contactuson.src = "/images/menu_contactus_on.gif";

 contactusoff = new Image();
 contactusoff.src = "/images/menu_contactus_off.gif";

 homeon = new Image();
 homeon.src = "/images/menu_home_on.gif";

 homeoff = new Image();
 homeoff.src = "/images/menu_home_off.gif";

 }