Terminal Services licensing

We will be deploying a Terminal Services Application server in the near future and was wondering how the Client licenses work. All of the clients that will connect to this server will be either Windows 2000 or XP pro. I was told that Microsoft recently changed their licensing in regards to Terminal Services. Currently as I understand it, because the clients will be Windows 2000 or XP the is no need to purchase any additional client access licenses. Is this still true?