function rollover(button, over)
{
  var link;

  if(over)
    link = 'http://www.daymedia.com.au/?site=3&common=/imgs/nav_' + button.name + '_over.gif';

  else
    link = 'http://www.daymedia.com.au/?site=3&common=/imgs/nav_' + button.name + '.gif';

  button.src = link;
}