"Consciousness is a kind of data processing and the brain is a machine that can be in principle replicated in other substrates, but general purpose computers are just not made of the right stuff."
The idea that we could make a computer conscious may be as fanciful as thinking we can make trees conscious or that we can make lobsters achieve human-level consciousness.
That would require consciousness to be based on physical processes that cannot be simulated by a computer. But in theory, all physical processes can be simulated by a computer, even quantum processes.
(Except possibly true randomness, but that can be achieved by plugging a true-random number generator card into the machine.)
Hypothetically an ordinary desktop computer, if given enough external memory and the right software, could simulate a human brain right down to the quantum level. (If you don't mind decades or even centuries passing in the real world for every second that passes in the simulation.)
But consciousness isn't the same thing as intelligence. A mouse would probably be conscious, so there would be no need to simulate a human brain to achieve consciousness.
Putting aside grandiose ideas of simulating a physical brain down to the quantum level to one side for the moment, I suspect that it would be possible to create a conscious program small enough to be stored on a DVD and capable of running on an ordinary PC. Of course, it'd be difficult to tell if you'd actually succeeded in generating consciousness without incorporating sufficient AI into the program to communicate coherently with it, and that might not be possible with a program of that size.
My concept of consciousness is basically that of an awareness feedback loop. An aware system (ie, a system capable of observing and analyzing sensory input to develop an understanding of the nature of the source of the sensory input) that possesses an awareness of it's own awareness. (I'm not sure if this description is fully coherent. Let me know if it makes sense to you.)
Also the poll assumes that all physical processes are computable.
The empirical evidence suggests otherwise.
Can you provide us with examples of non-computable physical processes?