// preload images ...
  var aMainMenu = new Array(18);
  for (i=0; i<18; i++) {aMainMenu[i] = new Image();}

  aMainMenu[0].src = 'http://www.qualityuvlamps.com/images/aquariumuv_on.gif';
  aMainMenu[1].src = 'http://www.qualityuvlamps.com/images/aquariumuv_off.gif';
  aMainMenu[2].src = 'http://www.qualityuvlamps.com/images/ponduv_on.gif';
  aMainMenu[3].src = 'http://www.qualityuvlamps.com/images/ponduv_off.gif';
  aMainMenu[4].src = 'http://www.qualityuvlamps.com/images/industrialuv_on.gif';
  aMainMenu[5].src = 'http://www.qualityuvlamps.com/images/industrialuv_off.gif';
  aMainMenu[6].src = 'http://www.qualityuvlamps.com/images/specialreq_on.gif';
  aMainMenu[7].src = 'http://www.qualityuvlamps.com/images/specialreq_off.gif';
  aMainMenu[8].src = 'http://www.qualityuvlamps.com/images/termscond_on.gif';
  aMainMenu[9].src = 'http://www.qualityuvlamps.com/images/termscond_off.gif';
  aMainMenu[10].src = 'http://www.qualityuvlamps.com/images/contactus_on.gif';
  aMainMenu[11].src = 'http://www.qualityuvlamps.com/images/contactus_off.gif';
  aMainMenu[12].src = 'http://www.qualityuvlamps.com/images/home_on.gif';
  aMainMenu[13].src = 'http://www.qualityuvlamps.com/images/home_off.gif';
  aMainMenu[14].src = 'http://www.qualityuvlamps.com/images/viewcart_on.gif';
  aMainMenu[15].src = 'http://www.qualityuvlamps.com/images/viewcart_off.gif';
  aMainMenu[16].src = 'http://www.qualityuvlamps.com/images/sitemap_on.gif';
  aMainMenu[17].src = 'http://www.qualityuvlamps.com/images/sitemap_off.gif';

  // swap menu images ...
  function swapMainMenu(sMainMenuName, nMainMenuIndex) {
    document[sMainMenuName].src = aMainMenu[nMainMenuIndex].src;
		return true;
  }