linq to xml(MOSS GetCurrentUser)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Xml;
using System.IO;
using System.Data;
using System.Data.Linq;
namespace XmlGetUserInfo
{
public class GetUser:WebPart
{
SPWeb sWeb;
SPUser currUser;
private string AddUser()
{
sWeb = SPControl.GetContextWeb(Context);
currUser = sWeb.CurrentUser;
XElement employees = null;
StringBuilder user = new StringBuilder();

//create and writer xml
//string strFilename = Environment.CurrentDirectory + @"\txtuser.xml";//get filename
string strFilename = System.AppDomain.CurrentDomain.BaseDirectory + @"\txtuser.xml";
if(!File.Exists(strFilename))
{
XmlWriterSettings xws=new XmlWriterSettings();
xws.OmitXmlDeclaration=true;
using (XmlWriter writer = XmlWriter.Create(strFilename,xws))
{
employees = new XElement("Root",
new XElement("Employee",
new XElement("Name", currUser.Name), new XElement("Email", currUser.Email)
)
);
employees.Save(writer);
}
}
else
{
employees = XElement.Load(strFilename);
XElement tree=new XElement("Root",
new XElement("Employee",
new XElement("Name", currUser.Name), new XElement("Email", currUser.Email)),
from el in employees.Elements()
select el);
TextReader tr = new StringReader(tree.ToString());
XElement xel =