string Application = Environment.GetEnvironmentVariable("windir") + @"\Notepad.exe";

     Dim Application As String = Environment.GetEnvironmentVariable("windir") & "\Notepad.exe"

static extern uint GetEnvironmentVariable(string lpName,

.NET Framework 2.0: Environment.GetEnvironmentVariable (String)

      MessageBox.Show(System.Environment.GetEnvironmentVariable("windir"))

Environment.GetEnvironmentVariable("windir");

    string getImg = Environment.GetEnvironmentVariable("windir") + "\\Web\\WallPaper\\Crystal.gif";

         var p = Process.Start(Environment.GetEnvironmentVariable("windir") + "\\notepad.exe");

     Dim p = Process.Start(Environment.GetEnvironmentVariable("windir") + "\notepad.exe")