Quantum computing is a different paradigm, you can't put a label on it such as "million times faster". For certain classes of problems, it gives an exponential speedup, which amounts to taking the logarithm of the running time (an operation which is not expressible by "x times faster" in the general case, since x gets bigger and bigger as the problem size grows). In other classes of problems (such as search), it gives a quadratic speedup, which amounts to taking the square root of the running time (again, not expressible as "x times faster" in general).
It's a totally different class of computing, which relies on very unintuitive physics, which (depending on taste) are best understood if you assume that there are parallel universes running different paths of the computation.
As Origin said, quantum computing is not going to replace traditional computing, since it's not applicable to all classes of problems. It can be used as a co-processor in a normal PC, if the PC needs to perform certain kinds of problems which benefit from the QC.
As for human brain emulation, it would be useful if the human brain relies on quantum effects, which is not known to be the case. However, by most estimates I've seen, traditional computing will be able to emulate a human brain in 20 years at most (at least in terms of hardware power, software is an unknown yet).
My Mario Kart Wii friend code: 2707-1866-0957
