Communism - the utopian ideology - didn't kill hundreds of millions of people, because it has never existed. It has been used several times as a means to reach power, after which the dictator(ships) have chosen to either adopt it to his/their own liking (Stalinism, Marxist-Leninism, Trotskyism, <insert>ism) or practically abolish it as is the case with modern-day China. Fully developed communism is supposed to (alas, probably never will) be 'a stateless, classless and moneyless society, structured upon common ownership of the means of production.' [1]

That's about as far from Stalinism you can get.

[1] http://en.wikipedia.org/wiki/Communism