So you're asking if the FCKGW version of XP is fine for a system that's not connected to the internet?
So I'll give you the benifit of the doubt & assume you're not, there are still several problems with running a base XP Pro without any updates. One example being Java applets & other Java based software will often fail to load and dump an error. Take even a legit retail XP Pro cd from the initial XP release, and you cannot run the latest versions of AIM or Weatherbug. Those are just examples I know of, there are sure to be others that fail to run properly, and don't have to be internet related as my known examples are.