function rollover(over,srcName,oImg){
 if(over) {
  n = srcName.length-4;
  url1 = srcName.substring(0, n);
  url2 = srcName.substring(n);
  oImg.src= url1 +'2'+url2;
 } else {
  n = srcName.length-5;
  url1 = srcName.substring(0, n);
  url2 = srcName.substring(n+1);
  oImg.src= url1 + url2;
 }
}