uses ..., tlhelp32;
...
{функция проверяет запущен ли сервис}
function IsRunning(sName: string) : boolean;
var
  Snapshot : THandle;
  ProcStruct : PROCESSENTRY32;
begin
  Result:= false;
  Snapshot:= CreateToolhelp32Snapshot(TH32CS_SNAPALL,  0 );
  if Snapshot =  0  then Exit;
  ProcStruct.dwSize:= SizeOf(PROCESSENTRY32);
  if Process32First(Snapshot, ProcStruct) then
  begin
    repeat
      if Pos(UpperCase(sName), UpperCase(ExtractFileName(ProcStruct.szExeFile))) =  1  then
      begin
        Result:= true;
        Break;
      end;
    until not Process32Next(Snapshot, ProcStruct);
  end;
  CloseHandle(Snapshot);
end;

  ...
  // Проверка для Firebird
  if not IsRunning('fbguard') then ShowMessage('Не запущен');