I probably can't answer you qeustion, for one simple reason - we don't know enough about the brain to simulate it. We are still learning how it works - how can you simulate something if you don't know how it works?
I'll give it a shot though:
Every neuron could be stored as a bit (on/off), and the state of the synapses as a byte (on/off, resistance) So you need a computer with at least 410 GB of RAM, to store the state of every neuron and syanpse (200 GB for neurons, 200GB for synapses, 10GB for calculations to run the simulation)
You need a proccesor/s fast enough to work out how all of those neurons and synapses interact, and update them all - thousands of times a second. This is assuming there are rules and algorithims for how electricity flows through the brain.
You need even more proccessing power and RAM to handle output from the brain and sensory input to the brain (and some way of getting sensory input).
You need to map neurons firing into thoughts - that may be impossible, meaning you would have a simulated brain that couldn't learn or control its world in any way.
So, for a simplified brain at the neuron/synapse level, you'll need a computer with maybe 500GB of RAM (which should preferably be cache for real-time simulation) and a 2 THz proccessor.
This will allow you to simulate a mathematical represenation of the brain, updating 1 million times a second (well, a little slower, as buses arnen't instantaneous and I'm rounding and simplifying a lot.)
The problem is not the hardware or software needed for the simulation, it's getting data to and from the simulation in a way the simulation (and you) will be able to interpret.
