if(document.images) {  //preload images
  dn0 = new Image()    ; 
  dn0.src="images/dn0.gif";
  dn1 = new Image()    ; 
  dn1.src="images/dn1.gif";
  p0 = new Image()    ; 
  p0.src="images/p0.gif";
  p1 = new Image()    ; 
  p1.src="images/p1.gif";
  wd0 = new Image()    ; 
  wd0.src="images/wd0.gif";
  wd1 = new Image()    ; 
  wd1.src="images/wd1.gif";
  cu0 = new Image()    ; 
  cu0.src="images/cu0.gif";
  cu1 = new Image()    ; 
  cu1.src="images/cu1.gif";     	
}


      function swap(imageName, imageFile) {
       if(!document.images)
			return;
		eval('document.images[imageName].src = '+imageFile+'.src');
	  }