function change_div(theDiv) {
	    if (theDiv == 1) {
		 document.getElementById('video_relay').className = "f_block_header_off f_on"; 
	   } 
	else   if (theDiv == 2) {
		 document.getElementById('wireless').className = "f_block_header_off f_on"; 
	   }
	else   if (theDiv == 3) {
		 document.getElementById('aim').className = "f_block_header_off f_on"; 
	   }
	else if (theDiv == 4) {
		 document.getElementById('captel').className = "f_block_header_off f_last f_on"; 
	   }
}