Process p1 = Process.Start(@"1.pptx");
Process p2 = Process.Start(@"2.pptx");

SetWindowPos(p1.MainWindowHandle, -1,
                        0,
                        0,
                       100,
                        100,
                        SWP_SHOWWINDOW);
SetWindowPos(p2.MainWindowHandle, -1,
                        200,
                        200,
                       100,
                        100,
                        SWP_SHOWWINDOW);

Process[] processlist = Process.GetProcesses();

foreach (Process process in processlist)
{
       if (!String.IsNullOrEmpty(process.MainWindowTitle))
       {
            Console.WriteLine("Process: {0} ID: {1} Window title: {2}", process.ProcessName, process.Id, process.MainWindowTitle);
       }
}