You need to change your language settings in Windows and for this you need the windows cd if you didn't install east asian language pack and chinese fonts in the beginning.
So, I guess your dog bited your original windows cd, but u are still a proud owner of a original key.
So don't feel shame and go to your local software dealer in Beijing where you should get also an english copy for 10RMB, or use the wellknown sources in the net.
As stitch said, there is a Howto thread in this forum (How to change language, not how to buy windows)