function CheckCommentForm() {
		if(!CheckEmpty('author','Por favor, coloque seu nome.')) return false;
		if(!CheckEmpty('email','Por favor, coloque seu e-mail (nunca vai aparecer no site, fique tranquilo(a))')) return false;
		if(!CheckEmpty('captcha_num','Por favor, responda a simples soma (\351 nosso anti-spam!) :)')) return false;
		if(!CheckEmpty('comment','Por favor, coloque um coment\341rio')) return false;
		if(!CheckCaptchaResponse()) return false;
		if(!CheckValidEmail('email')) return false;
		return true;
	}
	
	function CheckCaptchaResponse() {
		var captchaField = document.getElementById('captcha_num');
		
		var rand_a = document.getElementById('rand_a');
		var rand_b = document.getElementById('rand_b');
		var result = parseInt(rand_a.value) + parseInt(rand_b.value);
		if(parseInt(captchaField.value) != parseInt(result)) {
			alert('O n\372mero que voc\352 digitou est\341 errado! Dica: tente ' + result);
			return false;
		}
		return true;
	}
	
	function CheckValidEmail(fieldName) {
		var field = document.getElementById(fieldName);
	
		if (field.value.match(/^[A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4}$/i)) {
			return true;
		} else {
			alert('Voc\352 digitou um e-mail inv\341lido.');
			field.focus();
			return false;
		}
	}
	
	function CheckEmpty(fieldName, errorMessage) {
		var field = document.getElementById(fieldName);
		if(field != 'undefined') {
			if(field.value == '') {
				alert(errorMessage);
				field.focus();
				return false;
			}
		}
		return true;
	}
	
		//AJAX
	function xmlhttpPost(strURL) {
		var xmlHttpReq = false;
		var self = this;
		// Mozilla/Safari
		if (window.XMLHttpRequest) {
			self.xmlHttpReq = new XMLHttpRequest();
		}
		// IE
		else if (window.ActiveXObject) {
			self.xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
		}
		self.xmlHttpReq.open('GET', strURL, true);
		self.xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
		self.xmlHttpReq.onreadystatechange = function() {
			if (self.xmlHttpReq.readyState == 4) {
				//alert(self.xmlHttpReq.responseText);
			}
		}
		self.xmlHttpReq.send(null);
	}