function preloadImg() {
  if (document.images) {
  
    if (typeof(document) == 'undefined'){
	
      document = new Object();
}
    document.loadedImages = new Array();
    
    var argLength = preloadImg.arguments.length;
	
    for(arg=0;arg<argLength;arg++) {
      
      document.loadedImages[arg] = new Image();
      
      document.loadedImages[arg].src = preloadImg.arguments[arg];
		}
	}
}

function ImgCh(imgNum,imgSrc) {

  document.images[imgNum].src = imgSrc;


}