load_captcha = function() {
    new Ajax.Request('xp/captcha_block',{
	method: 'get',
	parameters:'get=1&time='+new Date().getTime(),
	onSuccess: function(transport) {
	    $$('#captcha_block #noscript')[0].hide()
	    $$('#captcha_block img')[0].src = "xp/captcha_img/"+transport.responseText+".jpg";
	    $$('#captcha_block input')[0].value = transport.responseText;
	}
    });
}

Event.observe(window, 'load', function(){
    $('captcha_refresh').observe('click', load_captcha );
    load_captcha();
});