Utopian Socialism?

Is the argument for Utopian socialism that Marx and Engels presented back in 1848 still valid today? Is it not possible to reform the system and thus break down the barriers capitalism has thrown up towards egalitarianism? It seems as if the problems faced during the writing of the Communist Manifesto have been somewhat nullified by the creation and legalization of the union, and various workers rights legislations which have been passed. Can the other violent aspects of communism be worked on and solved from within?

This raises another point, just simply looking at the basic assumption made in the previous paragraph. I was focusing on the US perspective on a capitalist state. Is it necessary for the entire world to be thrown in the turmoil of revolution for true communism to carry itself forward? Can a single state establish itself as a socialist state, and still successfully meld into communism while functioning within the confines of the capitalist world which surrounds it?