When I took the AP Euro exam and got a 5, Princeton Review was my best friend! I would recommend it over the textbooks, since the textbooks tend to have more information than you need. The only thing they're good for is if you're learning slowly throughout the year, or to look up information for an essay topic you can use for a variety of prompts, such as WW1 or the French Revolution or something.
Also, the REA flashcards are genius. Not the review book, they make a separate book of flashcards. At least two of the facts I learned from those flashcards were multiple choice questions on the test.
The "5 Steps to a 5" book isn't thorough enough, and in my opinion, a waste of time.