function mousein(imgID) {
  // get the image object we're referring to
  var thisimg = document.getElementById(imgID);
  // and add "_on" to its src
  //thisimg.src = thisimg.src.replace(/./i,"_hover.");
  thisimg.src = thisimg.src.replace(/(\.[a-z0-9]+)$/i,'_hover$1');
  //document.write(thisimg.src);
}
function mouseout(imgID) {
  // get the image object we're referring to
  var thisimg = document.getElementById(imgID);
  // and remove "_on" from its src0ppoo p[]
  thisimg.src = thisimg.src.replace(/_hover(\.[a-z0-9]+)$/i,'$1');
}