Daniel Dennett has some good stuff on this (see Consciousness Explained, etc). Its not that he knows the answers, but his point is that consciousness might not be exactly what we think it is, there are lots of thought-traps around it, so we have to carefully unpick some of our assumptions about it to get anywhere - e.g. what he calls the cartesian theatre is one very powerful misconception (too long to explain here).
Also I always like to drop this Iain Banks quote in these kinds of discussions (from A Few Notes About The Culture)
Certainly there are arguments against the possibility of [strong] Artificial Intelligence, but they tend to boil down to one of three assertions: one, that there is some vital field or other presently intangible influence exclusive to biological life - perhaps even carbon-based biological life - which may eventually fall within the remit of scientific understanding but which cannot be emulated in any other form (all of which is neither impossible nor likely); two, that self-awareness resides in a supernatural soul - presumably linked to a broad-based occult system involving gods or a god, reincarnation or whatever - and which one assumes can never be understood scientifically (equally improbable, though I do write as an atheist); and, three, that matter cannot become self-aware (or more precisely that it cannot support any informational formulation which might be said to be self-aware or taken together with its material substrate exhibit the signs of self-awareness). ...I leave all the more than nominally self-aware readers to spot the logical problem with that argument.
Edit: changed 'cant really avoid the conclusion' to 'its hard to ...'