So, just something to keep in mind. If you are planning on using AP credit to satisfy undergraduate course requirements, such as a BIO or PHYS class, most schools I know will not accept these as fulfilling their pre-requisites for med school. This isn't necessarily a problem, but just something to keep in mind. Most med schools will require 2 semesters of BIO w. lab, 2 sem of PHYS w/lab, 2 sem inorganic and 2 sem organic all w/ lab, some schools require calc, some want biochem, etc. So, if you're going to be a BIO major, then go ahead and take the AP credit, you will have plenty of other classes that will fulfill your requirements, likewise with the other sujects. However, if you are not interested in taking more than the required sciences, then make sure that you are getting them in college and not with AP credit.
I audited AP Bio my senior year of HS because I didn't really need the credit hours or the stress of maintaining an A in that class, but I wanted to learn the info (we had a great teacher/tough program). So, when I went to undergrad that class was an easy A, and that's where it matters.
Good luck all!