// PreLoad images...

if (document.images)
 {
  img1=new Image();
  img1.src="/inc/images/home_btn1.gif";
  img2=new Image();
  img2.src="/inc/images/home_btn2.gif";	
  img3=new Image();
  img3.src="/inc/images/info_btn1.gif";
  img4=new Image();
  img4.src="/inc/images/info_btn2.gif";
  img5=new Image();
  img5.src="/inc/images/library_btn1.gif";
  img6=new Image();
  img6.src="/inc/images/library_btn2.gif";
  img7=new Image();
  img7.src="/inc/images/catalog_btn1.gif";
  img8=new Image();
  img8.src="/inc/images/catalog_btn2.gif";
  img9=new Image();
  img9.src="/inc/images/store_btn1.gif";
  img10=new Image();
  img10.src="/inc/images/store_btn2.gif";
  img11=new Image();
  img11.src="/inc/images/contact_btn1.gif";
  img12=new Image();
  img12.src="/inc/images/contact_btn2.gif";
 }

// Change buttons function...

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