function rollOver (
	image, // the image ID
	file
){
  if (!file){
      // if a file isn't specified, assume it's obeying our naming convention
      // and replace the image with <filename>01.gif with <filename>02.gif 
    var currentSrc = document.getElementById(image).src;
    var start = currentSrc.lastIndexOf("/"); 
    var end = currentSrc.lastIndexOf(".gif")- 2; 
    var currentState = currentSrc.substring(end,(end + 2)); 
    if (currentState == "01")
      var newState = "02";
    else
      var newState = "01";

    file = currentSrc.substring(start,end) + newState + ".gif";
  }

  self.status = '';

  document.getElementById(image).src = 'images/buttons/' + file  

  return true;
}