This will launch the control panel itself:
  WinExec('rundll32 shell32.dll,Control_RunDLL',SW_SHOW);
"Display Properties" - Background:
  WinExec('rundll32 shell32.dll,Control_RunDLL desk.cpl,,0',SW_SHOW);
"Display Properties" - Screen Saver:
  WinExec('rundll32 shell32.dll,Control_RunDLL desk.cpl,, ',SW_SHOW);
"Display Properties" - Appearance:
  WinExec('rundll32 shell32.dll,Control_RunDLL desk.cpl,,2',SW_SHOW);
"Display Properties" - Settings:
  WinExec('rundll32 shell32.dll,Control_RunDLL desk.cpl,,3',SW_SHOW);