function swap(arg)
{
  fname = arg.src; cnt = fname.length; ext="";
  cnt-=4;
  ext=fname.substr(cnt,4);
  tp = fname.substr(cnt-2,2);
  nm = fname.substring(0, cnt-2);

  switch (tp) 
  {
   case "_1" : 
        tp = "_2"; 
      break; 
   case "_2" :
        tp = "_1";
	break;
  };
  arg.src = nm+tp+ext;
}

//M_preloadImages("imgs/button1_2.jpg", "imgs/button2_2.jpg", "imgs/button3_2.jpg", "imgs/button4_2.jpg", "imgs/button5_2.jpg");

function MM_preloadImages() { 
  var d=document;
  if(d.images){
	if(!d.MM_p) d.MM_p=new Array();
	var i,j=d.MM_p.length,a=MM_preloadImages.arguments;
	for(i=0; i<a.length; i++)
	    if (a[i].indexOf("#")!=0)
		{ d.MM_p[j]=new Image;
		  d.MM_p[j++].src=a[i];
		}
    }
}