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Your comment about how the brain can remain functional even if parts of it are lost reminds me of one of my high school teachers, who was actually missing a large section of his brain.  When he was a teenager, he hit his head while playing soccer and got a small bruise on his brain.  The bruise went unnoticed and developed a scab, which grew larger and larger until one day, years later, he passed out while driving and his condition was discovered.  He was told that the mass of "dead" brain tissue was quite large and needed to be removed.  Before his surgery, he underwent extensive testing, so that doctors could determine which sections of his brain were necessary to retain normal functioning, and which were safe to take out.  He told us that this testing process was unreal-when certain areas of his brain were probed, he was unable to respond to questions that the doctors were asking him, even though he was perfectly aware of what was being said.  Other areas, however, seemed to have no effect on his behavior.  Altogether, he had about 1/8 of his brain removed.  However, had he not shared this story with us, we never would have been able to tell.  His speech and all aspects of his behavior were completely normal.  So, the brain is indeed extremely resilient, and can deal with loss of function in large sections. 

You mention that computers can stop working if a single wire is broken or removed.  One major difference that I see between the brain and a computer is that the various boxes that make up the brain have a much higher degree of interconnection that the sections of a computer; for example, we learned that individual neurons form synapses with thousands of other neurons.  So, if one particular pathway no longer functions, there are probably many other pathways that can take over.  Perhaps this is one of the reasons why the brain as a computer is a "bad analogy."