Heh, I miss math....I'm a first year med student who majored in biochem during undergrad - really enjoyed math (maybe 'cause i love quantum mechanics). I never found calc hard - if you think about it, the theories are pretty simple but the applications are vast and you can get quite complicated very quickly. At my school, UNC Chapel Hill, Calc I is differential calc, Calc II is integral calc, Calc III is multivariable (which i think was the most challenging but interesting). Interestingly, the math courses that came after that, differential equations and linear algebra were quite a bit easer imho.
Oh yeah, a fellow math dude!