function effect(capa){
	//Desplegamos las capas
	if(capa == 'usada'){
		usadas.slideit();obranueva.slideup();anuncio.slideup();
	}
	if(capa == 'nueva'){
		usadas.slideup();obranueva.slideit();anuncio.slideup();
	}
	if(capa == 'anuncio'){
		usadas.slideup();obranueva.slideup();anuncio.slideit();
	}
}