Hi isaac_ho,
I bought my PowerBook G4 in Taiwan and got my MacOS X 7 days ago through AppleCare promotion (Buy AppleCare and we give you OS X for free).
Good news and bad news.
Good news is that you would not be able to update to 10.0.4 if you were using my OS X, which allows you to input Traditional Chinese characters.
Bad news is that your edition, the U.S. edition, I believe does not include Chinese input function because the Chinese community messed up and missed the boat.
Hopefully 10.1 will be a solution for both of us: me wanting a more responsive OS and you a Chinese input function.
I suggest you connect Apple or the reseller who sold you OS X.
Regards,
George Lien