China, growing and growing?

China keeps on growing and growing, supposedly. They are building up a military, resources and anything else they can get their hands on. It seems to be most beneficial for the globe for China to give the United States a run for their money, literally. China is giving the US, competition and therefore the standards of things are rising and making lifestyles improved. Since the Cold War, the US has been the world's single super power and now there is a chance that in the near future there could be two super power countries. The world has been somewhat stable globally with the US as our only super power, but would having two super powers set the world off better or worse?
With two super powers, there could definitely be tension and that can sometimes lead to war. Having the world's two super powers at war with each other would not be good for anyone, which is one of the downsides of having two as opposed to only one. Also, having the second super power being China, the rise of that country can easily effect smaller countries economy such as Japan where they blame the state of their economy on the rise of China. Other things such as the rise of their military could lead to problems as well because it increasing so fast that it needs to be monitored.
Overall, I'm uncertain whether or not having two super powers is such a good thing.