I don't trust agents that I don't know. They are usually useless in my experience. Either work with someone in your own company who is based in China, or do it yourself.
I walked up to the Chinese Consulate in Melbourne last year bringing a passport photo and filled out the papers while standing in line. When I got to the desk, they told me that U.S. citizens had to do everything in duplicate. This is because the U.S. requires Chinese visitors to do everything in duplicate.
So I went to the local photo shop and got an extra picture, went back and filled out a second application, came back the next day and picked up my visa.
I later learned that the secretary in my company's Hong Kong office can process Chinese visa in a matter of a few hours. Without bothering with pictures!
[This message has been edited by stimpy (edited 04-23-99).]