The book I used (that I REALLY liked) was actually Kaplan. It was one of the books with the interactive CD. What I particularly liked was that the CD had a diagnostic test which could tell you where your weaker areas were, and then had a study plan put together based on what those weaknesses were. Also, there were vocab games on the CD. I had NO desire to sit down and memorize hundreds of words, but after playing the games my competetive nature kicked in and I'd sit down to memorize words just so I could do better on the games. Plus it's a fun way to reinforce what you've learned, and find out what words you're not remembering.
As for the math, my Kaplan book (and something I would look for particularly) had a "100 things you need to know for the GRE math section" portion of the book. Most of it was stuff I kinda knew how to do, but "tricks" I'd forgotten or never learned (e.g. how do you find the least common multiple of 24 and 52? This problem can take forever, but if you know the "trick" it'll take you less than 30 seconds). There were multiple problems on my actual GRE that, as I was solving, I realized I wouldn't have been been able to solve (or it would have taken me FOREVER to solve) if I hadn't have known those hundred things.
Finally, as others have said, take practice tests!!!! (Again, the interactive CD I used had, I think, 6 full length practice tests I could take). I had a friend who easily could have gotten 750 or higher on her verbal GRE section, but because she'd never done it timed before, her score went down. There's nothing quite like sitting at the computer and actually going through the motions to find out your strengths and weaknesses, and to make you feel more comfortable on test day. Plus it's a good way to track your progress.
Oh, one last thing. When you're actually taking the test, make sure to go in with the confident attitude of "I'm going to own this test, I know what I'm doing. And if I see a problem I don't know how to do, it's okay -- I'll figure it out." I swear to you, it sounds corny, but taking tests with that attitude makes you second-guess yourself less and I can just about promise you you'll do better. And when you're driving on the way to take your test, I highly recommend putting in a CD you LOVE and ROCKING OUT to it on the way. I mean seriously, singing-along-loudly-dancing-in-the-car type rocking out. I did that and it helped calm my nerves and put me into a really good mindframe for taking the test. (Just make sure it's not songs that you won't be able to get out of your head