if(document.images) {
 var imgs = new Array();
 imgs[0] = new Image();  imgs[0].src = "images/menu/m01_def.gif"; 
 imgs[1] = new Image();  imgs[1].src = "images/menu/m01_over.gif";
 imgs[2] = new Image();  imgs[2].src = "images/menu/m02_def.gif";
 imgs[3] = new Image();  imgs[3].src = "images/menu/m02_over.gif";
 imgs[4] = new Image();  imgs[4].src = "images/menu/m03_def.gif";
 imgs[5] = new Image();  imgs[5].src = "images/menu/m03_over.gif";
 imgs[6] = new Image();  imgs[6].src = "images/menu/m04_def.gif";
 imgs[7] = new Image();  imgs[7].src = "images/menu/m04_over.gif";
}

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}