The only thing I would look at if you haven't already had a course in it is anatomy. Get the Netter Atlas of Human Anatomy. You WILL use it next year and it is the kind of book that is easily "browsed" through. You might also like the Rohen Photographic Atlas--I use both.
The standard physiology textbook is Berne and Levy's Medical Physiology, though I wouldn't buy it now. It is very dense and your school also might end up using something else.
Other than that, you may well end up using some of the same texts you had as an undergrad (we used Cooper's Cell Biology, same as undergrad), particularly for cell biology review and possibly biochemistry. The Board Review Series are great books for subject review and I'd say you probably can't go wrong with those in most subjects.
I don't know the specifics for PCOM or NYCOM...but I will say this, don't listen to people who tell you not to buy textbooks or even certain texts. You will develop a method that is best for you and it may well be reading everything assigned to you (that's pretty much what I do and it's working for me). Others rarely read or just glance over the reserve copies in the library.
Take all advice (including mine) with a grain of salt--then figure it out for yourself.
best of luck!
