home_on       = new Image();
home_off       = new Image();
home_on.src = "images/menu/home_on.gif";
home_off.src = "images/menu/home_off.gif";

about_on       = new Image();
about_off       = new Image();
about_on.src = "images/menu/about_on.gif";
about_off.src = "images/menu/about_off.gif";

profile_on       = new Image();
profile_off       = new Image();
profile_on.src = "images/menu/profile_on.gif";
profile_off.src = "images/menu/profile_off.gif";

practice_on       = new Image();
practice_off       = new Image();
practice_on.src = "images/menu/practice_on.gif";
practice_off.src = "images/menu/practice_off.gif";

contact_on       = new Image();
contact_off       = new Image();
contact_on.src = "images/menu/contact_on.gif";
contact_off.src = "images/menu/contact_off.gif";

resources_on       = new Image();
resources_off       = new Image();
resources_on.src = "images/menu/resources_on.gif";
resources_off.src = "images/menu/resources_off.gif";

choose_on       = new Image();
choose_off       = new Image();
choose_on.src 	= "images/menu/why_choose_on.gif";
choose_off.src = "images/menu/why_choose_off.gif";


function button_on ( imgId ){
  if ( document.images )  {
    butOn = eval ( imgId + "_on.src" );
    document.getElementById(imgId).src = butOn;
  }
}

function button_off ( imgId ){
  if ( document.images )  {
    butOff = eval ( imgId + "_off.src" );
    document.getElementById(imgId).src = butOff;
  }
}