Treeview explorer fra bestemt folder

Kode 

private void button1_Click(object sender, EventArgs e)
        {
            DirectoryInfo dir = new DirectoryInfo(@"C:\Users\Administrator\Documents\Visual Studio 2010\Projects");

            GetDirs(dir);
        }

        private void GetDirs(DirectoryInfo dirInfo)
        {
            TreeNode Main = treeView1.Nodes.Add("Mapper");
            Main.Tag = "";
            foreach (DirectoryInfo info in dirInfo.GetDirectories())
            {
                TreeNode MainNext = Main.Nodes.Add(info.Name);
                MainNext.Tag = (info.Name);

                GetSubDirs(info, MainNext);
            } 
        }

        private void GetSubDirs(DirectoryInfo dirInfo, TreeNode aNode)
        {
            foreach (DirectoryInfo info in dirInfo.GetDirectories())
            {                
                aNode.Nodes.Add(info.Name);

                foreach (FileInfo file in info.GetFiles())
                {
                    TreeNode bNode = new TreeNode(file.Name);
                    aNode.Nodes.Add(bNode);
                }
            } 
        }