function validate_form(thisform) {
	with (thisform) {
		if (validate_req(first_name,"First Name is required!")==false) {
			return false;
		}
		
		if (validate_req(last_name,"Last Name is required!")==false) {
			return false;
		}
		
		if (validate_req(email,"E-mail is required!")==false) {
			return false;
		}
		if (validate_email(email,"Not a valid e-mail address!")==false) {
			return false;
		}
		
		if (validate_req(comment,"Comments is required!")==false) {
			return false;
		}
	}
}

function validate_req(field,alertTxt) {
	with (field) {
	  if (value==null||value=="") {
	  	alert(alertTxt);return false;
	  } else {
	  	return true;
	  }
	}
}

function validate_email(field,alertTxt) {
	with (field) {
		apos=value.indexOf("@");
		dotpos=value.lastIndexOf(".");
		if (apos<1||dotpos-apos<2) {
			alert(alertTxt);
			return false;
		} else {
			return true;
		}
	}
}