Yes, "nègre" can be pejorative, and sometimes equivalent to the american N-word; but for a while, it was also the plain term the French used for anybody hailing from Africa. That's why my Petit Robert says the word is "Vieilli ou Péjoratif: Personne de race noire (...)". "Nègre" was also used to decribe African slaves, hence perhaps one reason why people eventually objected to the term.
On the other hand "négro" IS the French N-word. One that's only "Péjoratif" and categorized as "injure raciste".
The problem I have with what JPG said is not the word "nègre", unlike many here. It's when he says "I don't know if they every worked." People should stop hunting the evil words, and look for the ideas instead. In my opinion, his stupidity is much clearly visible therein than in the ambiguous (dated? racist?) usage of the word "nègre".
BTW, I'm a francophone Montrealer.