Finally, a topic that tests my what I've learnt so far in school! Sophist, to respond to your original question: economically, there really are not many critiques of capitalism. Adam Smith was the greatest supporter of this type of system in which the government practiced "laissez-faire." Keep in mind, however, that there is not one country that has practiced this completely. On a scale, though, the US is closest in terms of similarity. The social inequities that result from this system are regarded as almost inevitable, since there has to be individuals who are the workers, others who are the owners, etc. I see that some people are suggesting communism to be a better solution, but I think they're confusing a political ideology with economic theory. The economic opposite to a capitalist economy is a command economy (practiced by the former Soviet Union, China, etc.), and history has clearly proven the faults of this type of system. Sophist, you mentioned market socialism, the route that China is currently testing, because they have also realized the great faults of a command economy.
I want to emphasize that the most stable economic system is one that is based on a free market. When humans attempt to manipulate and control beyond their powers (eg. Soviet communism), we know very well the outcome. As China incorporates free market characteristics into its otherwise planned economy, they're hoping to avoid the fate of their doomed counterpart.
One more thing, let's not confuse socialism with communism, or even socialism with welfare states (Daanger, you said Sweden is a socialist state, but it's really a social democracy (like Canada) with an extremely developed welfare state). And in terms of healthcare systems, the US system is only advanced by a tiny margin from that of Cuba's (I believe their rankings are 27 and 29).
I'm sorry to have written so long, but this is really a loaded question.
Anyways my point is that a free market is the only truly stable system, and perhaps even more equitable since the laws of supply and demand allocate resources accordingly. My ideal system? A social democratic welfare state with a free-market economy.