function getXhr()
{
	var xhr = null; 
	if(window.XMLHttpRequest) // Firefox and others
	   xhr = new XMLHttpRequest(); 
	else if(window.ActiveXObject){ // Internet Explorer 
	   try {
				xhr = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
				xhr = new ActiveXObject("Microsoft.XMLHTTP");
			}
	}
	else { // XMLHttpRequest not supported by brownser
	   alert("Your browser doesn\'t support object XMLHTTPRequest..."); 
	   xhr = false; 
	} 
	return xhr;
}

function IsNumeric(sText)
{
   var ValidChars = "0123456789.";
   var IsNumber=true;
   var Char;
   for (i = 0; i < sText.length && IsNumber == true; i++) 
   { 
      Char = sText.charAt(i); 
      if(ValidChars.indexOf(Char) == -1) 
      {
      	IsNumber = false;
      }
   }
   return IsNumber;
}