No! First, for Marx, "productive labor" is labor that produces surplus-value. Your definition (and that of the Soviets) is from Smith, not Marx. (It might be argued, incorrectly to my mind, that the production of physical products is a necessary step allowing the production of surplus-value, but it's the latter that _defines_ "productive labor.")
Second, to say that only "productive workers" are "really workers" is to adopt the perspective of the capitalist class as a whole. It's the capitalist class as a whole that benefits from the production of surplus-value (in capitalist society). The production of surplus-value is also relevant to crisis theorists, but it isn't relevant to issues of the social relations of production, the organization of a counter-hegemonic movement, etc.
(Marx himself said that being a productive laborer is a misfortune. See ch. 16 of vol. I for that and a summary of his perspective.)
Jim Devine jdevine at popmail.lmu.edu & http://clawww.lmu.edu/Departments/ECON/jdevine.html "he who is unable to live in society or has no need, because he is sufficient for himself, must be either a beast or a god." -- Aristotle