<!--
function MM_preloadImages() {
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
} 
//-->

   var button1_off = "images/btn_1.png";
   var button1_on = "images/btn_1_over.png";
   var button1_5_off = "images/btn_1_5.png";
   var button1_5_on = "images/btn_1_5_over.png";
   var button2_off = "images/btn_2.png";
   var button2_on = "images/btn_2_over.png";
   var button3_off = "images/btn_3.png";
   var button3_on = "images/btn_3_over.png";
   var button4_off = "images/btn_4.png";
   var button4_on = "images/btn_4_over.png";

   function activate(imgName) {
      document.images[imgName].src = eval(imgName + "_on");
   }

   function deactivate(imgName) {
      document.images[imgName].src = eval(imgName + "_off");
   }