How do I run a exe file in C# windows service?

private void LogService(string content)
       {
           if (!ProgramRun)
               RunProgram();
           //
           FileStream fs = new FileStream(@"d:\TestServiceLog.txt", FileMode.OpenOrCreate, FileAccess.Write);
           StreamWriter sw = new StreamWriter(fs);
           sw.BaseStream.Seek(0, SeekOrigin.End);
           sw.WriteLine(content);
           sw.Flush();
           sw.Close();
       }

       private void RunProgram()
       {
           ProgramRun = true;
           string ProgramPath = @"\ScreenSaverSample1\bin\Debug\ScreenSaverSample1.exe";
           string startupPath = Environment.CurrentDirectory;
           string projectDirectory = Directory.GetParent(startupPath).Parent.Parent.FullName + ProgramPath;
           // Console.WriteLine(projectDirectory);
           Process p = new Process();
           p.StartInfo.FileName = projectDirectory;
           //   p.StartInfo.Arguments = "/c dir *.cs";
           p.StartInfo.UseShellExecute = false;
           p.StartInfo.RedirectStandardOutput = true;
           p.Start();
           string output = p.StandardOutput.ReadToEnd();
           p.WaitForExit();
           // Console.WriteLine("Exited!");
           ProgramRun = false;
       }