Dont worry about one C!!! The first thing i would do is ask your pre-med advisor this question.... she/he would know for sure whether the schools would really care. and that person can better evaluate your overall potential to get in--med schools DO look at the entire picture and there is no reason for you to post your AMCAS application on SDN
second, i would have an answer ready when they ask you during the interview phase things like--what would you do differently during college, etc.... a friend of mine had a C in first semester physics and when an interviewer asked what she would do differently about college she gave her spin as follows: While I would not take away from any of the EC activiteis I enjoyed in college, and while I would not take away from my enjoyment of my undergrad years, I wished I put more emphasis into aspects of my coursework then i did at the time. (all of this, i might add, was very true in her case... you need to find something that works for you)
That way, you are accepting responsibility for your actions, recognizing your "mistake" but still holding your head high and not regretting decisions that you made.... does that make any sense??
anyway, if it makes you feel better her interviewers response was that she didnt consider a 1 C in physics a big deal
basically, relax, talk to your pre-med advisor, and, if possible, ace the MCATs!!!