SetGlobalEnvironment('FIREBIRD', FolderWithfbclient_dll);

function SetGlobalEnvironment(const Name, Value: string; const Local: Boolean = True;
  const User: Boolean = True): Boolean;
resourcestring
  REG_MACHINE_LOCATION = 'System\CurrentControlSet\Control\Session Manager\Environment';
  REG_USER_LOCATION = 'Environment';
begin
  Result := Local;
  SetEnvironmentVariable(PChar(Name), PChar(Value));
  if not Result then
  with TRegistry.Create do
  try
    if User then { User Environment Variable }
      Result := OpenKey(REG_USER_LOCATION, True)
    else { System Environment Variable }
    begin
      RootKey := HKEY_LOCAL_MACHINE;
      Result  := OpenKey(REG_MACHINE_LOCATION, True);
    end;
    if Result then
    begin
      WriteString(Name, Value); { Write Registry for Global Environment }
      { Update Current Process Environment Variable }
      SetEnvironmentVariable(PChar(Name), PChar(Value));
      { Send Message To All Top Window for Refresh }
      SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, Integer(PChar('Environment')));
    end;
  finally
    Free;
  end;
end;