How do I execute another program from my Delphi application 2

{ Useage: Filename, The file to be executed
          Params, Any parameters that require passing to the file
          Timeout, Time to wait in mS. Pass the constant INFINITE to wait forever
          Visibility, Run window status e.g SW_SHOW, SW_MAXIMIZE
          It returns a string containing the last error if any
}
function WaitProcess(Filename: TFilename; Params: string;
         Timeout: DWORD; Visibility: integer): string;
var StartupInfo: TStartupInfo;
    ProcessInfo: TProcessInformation;
    WaitResult: integer;
begin
   ZeroMemory(@StartupInfo, SizeOf(TStartupInfo));
    with StartupInfo do
      begin
         cb := SizeOf(TStartupInfo);
         dwFlags := STARTF_USESHOWWINDOW or STARTF_FORCEONFEEDBACK;
         wShowWindow := Visibility;
       end;
    if fileexists(filename) or fileexists(params) then
      begin
         if (CreateProcess(nil, Pchar(Filename +' '+ Params), Nil, Nil,
                     False, NORMAL_PRIORITY_CLASS,
                     Nil, nil { pchar(extractfilepath(Params))}, StartupInfo, ProcessInfo))
            then
                begin
                    WaitResult := WaitForSingleObject(ProcessInfo.hProcess, Timeout);
                    if WaitResult = WAIT_TIMEOUT then
                       begin
                          result := 'Timeout has occured in waiting for result from compiler.';
                          TerminateProcess(ProcessInfo.hprocess, 1);
                          CloseHandle(ProcessInfo.hProcess);
                          CloseHandle(ProcessInfo.hThread);
                          exit;
                       end;
                    CloseHandle(ProcessInfo.hProcess);
                    CloseHandle(ProcessInfo.hThread);
                    Result := 'OK';
                end
            else
                result := 'Create Proccess failed ' + filename + ' '+ Params+ ' Error: '+inttostr(getlasterror);
      end
   else
      result := 'Process file does not exist';
end;