One of the ways you will often hear Calvin described is fatalistic (i.e., since God is sovereign over all things, it doesn't matter what we do and thus things like prayer become meaningless). Of course, those who describe him in this way rarely know anything about him and have probably never read anything by him. But this characteristic is clearly dispelled in the portion that I read this morning from Book III, Chapter 20 - "Of Prayer - A Perpetual Exercise of Faith. The Daily Benefits Derived from It."
Does this sound like someone who believes in fatalism?
It is very absurd, therefore, to dissuade men from prayer, by pretending that Divine Providence, which is always watching over the government of the universe, is in vain importuned by our supplications, when, on the contrary, the Lord himself declares, that he is "nigh unto all that call upon him, to all that call upon him in truth" (Ps. 145:18).