function createRequest()
{
var request=null;
     try {
       request = new XMLHttpRequest();
     } catch (trymicrosoft) {
       try {
         request = new ActiveXObject("Msxml2.XMLHTTP");
       } catch (othermicrosoft) {
         try {
           request = new ActiveXObject("Microsoft.XMLHTTP");
         } catch (failed) {
           request = null;
         }
       }
     }

     if (request == null)
      {
	  alert("Error creating request object!");
	  }
	  else
	  {
	  return request;
	  }
}
var request1=createRequest();	  
  
<!-- Создание запроса request -->

function xmlzapros2()
{
var url="/order.php";

request1.open("POST", url, true);
request1.onreadystatechange=xmlotvet2;

request1.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
var n=document.getElementById("name").value;
var h=document.getElementById("href").value;
var c=document.getElementById("city").value;
var t=document.getElementById("text1").value;
var k=document.getElementById("kapcha").value;
var s=document.getElementById("sid").value;
var cat=document.getElementById("id_cat").value;
request1.send("name="+n+"&href="+h+"&city="+c+"&text="+t+"&kapcha="+k+"&sid="+s+"&id_cat="+cat);
document.form[0].reset();

}
function xmlotvet2()
{
	if(request1.readyState==4)
	{
		if(request1.status==200)
		{
		var response=request1.responseText;
		
		var otvet=document.getElementById("text");
		
		
		var mainDiv =document.getElementById("main2");
		var secondDiv =document.getElementById("id_form2");
		pElement=document.createElement("p");
		textNode=document.createTextNode(response);
		pElement.appendChild(textNode);
		mainDiv.replaceChild(pElement, secondDiv);
		}
		else
		{
		alert("Ошибка"+request1.status);
		}
	}
}


function proverka_name(name1)
{

var template1 = /^[A-Za-zА-Яа-я]+$/;

if(template1.test(name1))
{
t='OK';
}
else
{
t='Ошибка';
}


replaceText(n1, t);
}

function check_href(href)
{

var template1 = /^[A-Za-z0-9\./':']+$/;

if(template1.test(href))
{
t='OK';
}
else
{
t='Ошибка';
}


replaceText(h1, t);
}

function check_city(city)
{

var template1 = /^[A-Za-zА-Яа-я]+$/;

if(template1.test(city))
{
t='OK';
}
else
{
t='Ошибка';
}


replaceText(c1, t);
}

function proverka_text2(text)
{

var template1 = /^[A-Za-zА-Яа-я0-9\.]+$/;

if(template1.test(text))
{
t='OK';
}
else
{
t='Ошибка';
}


replaceText(n2, t);
}

function check_cat(cat)
{

var template1 = /^[0-9]+$/;

if(template1.test(cat))
{
t='OK';
}
else
{
t='Ошибка';
}
replaceText(cat1, t);
}