// Ajax username check.
function checkUser( username )
{
var xmlHttp;
try
  {
  // Firefox, Opera 8.0+, Safari
  xmlHttp=new XMLHttpRequest();
  }
catch (e)
  {
  // Internet Explorer
  try
    {
    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
  catch (e)
    {
    try
      {
      xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
      }
    catch (e)
      {
      alert("Your browser does not support AJAX!");
      return false;
      }
    }
  }
  xmlHttp.onreadystatechange=function()
    {
    if(xmlHttp.readyState==4)
      {
		if( xmlHttp.responseText == "true" )
			document.getElementById('usernameerror').innerHTML = "Username <i>" + username + "</i> already exists!";
		else
			document.getElementById('usernameerror').innerHTML = "Username <i>" + username + "</i> is available.";
      }
    }
  xmlHttp.open("GET","getuser.php?p=" + username,true);
  xmlHttp.send(null);
}