Casey is right. MKSAP (especially II) is golden. I would read a review (Blueprints, First-Aid, etc) quickly during the first half of rotation to help with pimp questions, then focus on question books.
1. MKSAP II (***)
2. Pretest
3. Harrisons question book
4. Appleton and Lang
MKSAP and maybe Pretest should be enough, but these are two other books just in case you were wanting to go crazy.