you should try ctrip.com, they have an english version, and should be able to accept payment by credit card (US based). They are like orbitz of US, have air fares from a variety of chinese airlines, and they also have some contract fares negotiated directly with the airlines.

Kuxun.com (or kooxoo.com, same site), on the other hand, is like Kayak.com, so it compares fares from a variety of website, but do not sell you tickets directly. I don't think they have an english page yet.