function imgHover(id,tag){
      var sfEls = $(id).getElementsByTagName(tag);
      for (var i=0; i<sfEls.length; i++) {
            sfEls[i].onmouseover=function() {  
                  if (this.className.search("rollOver")>=0){
                        if (this.src.search("jpg")>=0){
                             this.src=this.src.replace('.jpg','_a.jpg');
                        }else{
                             this.src=this.src.replace('.gif','_a.gif');
                        }
                  }
            }
            sfEls[i].onmouseout=function() {
                  if (this.className.search("rollOver")>=0){
                        if (this.src.search("jpg")>=0){
                             this.src=this.src.replace('_a.jpg','.jpg');
                        }else{
                             this.src=this.src.replace('_a.gif','.gif');
                        }
                  }
            }
      }
}