Stratfor has an interesting discussion on China.
I think China will peak before surpassing us. I think China can't afford to be a land power (which they must be) and a significant naval power big enough to chase us out of the western Pacific. We will be more powerful than China for a long time and our deployable power will always be greater even if China's GDP passes ours for a while. If mobilized, we can defeat China even in the western Pacific--as long as we retain our allies such as South Korea, Japan, Taiwan, and others further back.
The problem is, China doesn't need to defeat us. All the talk of whether China can surpass us in power (they will not) and whether China's military power can defeat us even in the western Pacific (they cannot, over time) ignores the basic point that Chinese objectives involve defeating neighbors who are much smaller. China only needs to delay us and prevent us from defeating China while China defeats the neighbor they choose to attack.
The second part of that problem is that we might not have the time to roll back any Chinese gains while they take advantage of their geographic proximity to targets and our distance. We might not have that time because we forget what it is like to face conventional warfare against a nuclear-armed power able to hit our cities. Since we won the Cold War, we've gotten used to being able to fight enemies for years without worrying that outside forces can stop us with the threat of nuclear war. But when the threat of nuclear escalation from a conventional clash with China looms, will we continue the conventional fight to regain lost ground? I don't know.
That's the problem of China's rise. They aren't going to take our place as the dominant global power, and we will have the advantage if it comes to a general war. But China is gaining the power to delay us long enough to beat their primary targets. We need to make sure the local targets can survive long enough to make sure that the threat of nuclear escalation deters China from completing their conventional missions. If local targets are strong enough to fight without our direct intervention rather than our support with supplies and intelligence, Chinese threats to escalate to nuclear levels will be less credible.
There is no reason to fear China. But there is reason to cope with them.