I realize you are "starting members" but it doesn't appear as if you guys have researched this much at all. Go to the upper right corner of this page and Click "search". Enter "Vietnam" or "China" and you will get many pages of posts regarding both places.
The latest one that gives you a good summary of how futile your plans for China may be is from "Skip": http://board.gt-rider.com/topic.asp?TOP ... hichpage=2
What kind of bikes? Are you aware of the 175cc limit for Vietnam? Read more and then ask some specific questions if you have them.
Ever notice that "What the Heck!" is usually the right answer?
At present, entering Vietnam with a bike is most likely impossible. We tried last December, and we even went with small (under 175cc) bikes or scooters, because it was supposed to work better. It didnt, we tried every 3 international border stations between Cambodia/Vietnam, one of them we tried twice, and then went into Laos and tried at the Laobao border. The final answer was NO every time, though there was a lot of confusion with the officials. They didnt really seem to know what to do with us, and decided to opt on the side of caution. We were a group of 8, maybe just MAYBE, if there wouldve been only 1-2 people, it could´ve been a different story, but I doubt it. They just didnt like the idea of letting falangs go with their own bikes.
Its sad, but at the moment in this region you can "only" go to Thailand, Cambodia & Laos with your own bike. Only is of course a wrong word, these are all wonderful places to travel and explore! But try Vietnam, China & Myanmar and you (or your bike, that is) will most likely run against a solid concrete wall of bureaucracy. You hear the stories like someone getting into Vietnam, but it surely doesnt happen very often, so you shouldnt plan that you *WILL* get in.