ns4 = (document.layers)? true:false
ie4 = (document.all)? true:false


function opwin(url,vent,barra,scrol,ancho,alto)
	{
			open(""+url+"",""+vent+"","menubar="+barra+",width="+ancho+", height="+alto+", scrollbars="+scrol+", top="+((winH/2)-(alto/2))+", left="+((winW/2)-(ancho/2))+"")
	}