I know calculus is a pre-req for some schools, but I don't think they look at it very closely as compared to some of the others- like those tested on the OAT. I got college credit from my high school calc class. (It technically comes in as transfer credit, from a University at home.) I do think I got an A, but no one ever mentioned the odd situation to me or anything. (I only applied to IU, and got accepted.)
I suspect that a low grade in calculus would not matter less than one in Chem or Bio, but I guess more than one in English or something. But I think one low grade is really not going to matter that much, as long as it's not a habit.
