Awe the sarcasm of SDN in response to a legitimate (Okay, I personally think you should bask in your freedom all summer, but if you must...) question.
The following seem to be THE books to get:
Atlas of Anatomy by Netter
Clinical Microbiology Made Ridiculously Simple
Other options:
A histology atlas (Like Wheater's - some people don't think this is necessary)
Color Atlas of Anatomy (varied response on whether or not this is needed - it has pretty pictures anyway that are color coded!)
Grant's Dissector (However, this book could also be bought between you and your lab partners).
Personally, I'd stick with Netter's if you absolutely feel like you need a book to start and leave it at that before you get guidance from students at the med school you're going to attend (Recognizing of course that Netter's is pretty much just some awesome drawings and not exactly a sit down and read book). As for Harrison's and such, there's no way you'll have time to get to it with all of the binders worth of med lecture slides. Stick to up-to-date and online versions of textbooks provided for free by your school/in the library instead.