In addition to the good answer given,
A marxist pushes for social equality. According to marxists, distribution of resources has flawed capitalism creating a perpetual class struggle between proletariat (working class) and bourgeoisie (owners). He predicted that most capitalist regimes would eventually face such a strong class-divide, that the proletariat would come together and revolt against the oppressive bourgeoisie.
To me, Marxism is more of a philosophical concept that requires deep personal transformation. Equality for all is a huge pill to swallow for most people. We like buying new ipods, cameras, and cell phones. However it makes me sound, I have found comfort in expressing myself through the clothes i buy, and the car I drive.
Marx makes important observations about the dyamics of capitalist and socialist theories. But as far as being practical, Marxism is not an ideology, on its own, that would ever realistically function; people are self-serving creatures.
Contrary to popular belief, Cubans DONT think its awesome to have to drive around in 1940s-50s American cars.