Traversing through Drive C#

It is quite easy to traversing through the Files and Directory in a given drive or folder:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace DirectoryIterator
{
  class DirectoryTraverser
  {
    String _Source = String.Empty;
    private SortedSet SystemFiles = new SortedSet();

    DirectoryTraverser(String source)
    {
      _Source = source;
      this.NoteSystemFiles();
    }

    private void NoteSystemFiles()
    {
      SystemFiles.Add("$RECYCLE.BIN");
      SystemFiles.Add("System Volume Information");
    }

    void iterateAll()
    {
      DirectoryInfo dir = new DirectoryInfo(_Source);

      foreach (var file in dir.GetFiles())
      {
        // Do something with files
      }

      foreach (var subDir in dir.GetDirectories())
      {
        if (!SystemFiles.Contains(subDir.Name))
        {
          // do something with sub dir
        }
      }
    }
  }
}

Please let me know if I miss something.

Thanks
Enjoy Coding.