// PreLoad images...

if (document.images)
 {
  img1=new Image();
  img1.src="images/button_join.jpg";
  img2=new Image();
  img2.src="images/button_join_over.jpg";	
  img3=new Image();
  img3.src="images/button_directory.jpg";
  img4=new Image();
  img4.src="images/button_directory_over.jpg";
  img5=new Image();
  img5.src="images/button_friend.jpg";
  img6=new Image();
  img6.src="images/button_friend_over.jpg";
 }

// Change buttons function...

function ChangeImage(imagen1,imagen2)
{
  if (document.images) imagen1.src=imagen2.src;
}