function preload(){
 this.length=preload.arguments.length;
 for (var i=0; i<this.length; i++){
  this[i]=new Image();
  this[i].src=preload.arguments[i];}}

imgs=new preload(
"images/menu1b.gif",
"images/menu2b.gif",
"images/menu3b.gif",
"images/menu4b.gif",
"images/menu5b.gif",
"images/menu6b.gif",
"images/menu7b.gif"
);

function on(PicName){
 document[PicName].src='images/'+PicName+'b.gif';
}
function off(PicName){
 document[PicName].src='images/'+PicName+'.gif';
}