if (document.images) {
  img1=new Image; img1.src="images/link1.gif";
  img2=new Image; img2.src="images/link1_on.gif";
  img3=new Image; img3.src="images/link2.gif";
  img4=new Image; img4.src="images/link2_on.gif";
  img5=new Image; img5.src="images/link3.gif";
  img6=new Image; img6.src="images/link3_on.gif";
  img7=new Image; img7.src="images/link4.gif";
  img8=new Image; img8.src="images/link4_on.gif";
  img9=new Image; img9.src="images/link5.gif";
  img10=new Image; img10.src="images/link5_on.gif";
}