Like Effem said, I found the GRE to be pretty similar to the SAT's as far as math went. The verbal section was much harder IMO, and included tons of random words that I will likely never see or hear again in my life. A friend of mine had the Kaplan test guide, and I just skimmed over it for some of the math sections I was weaker on...which was a nice little refresher. I didn't study at all for the verbal.
A doctoral student that I know said he had the "Webster's Word of the Day" daily calendar, and surprisingly many of those words were on the test when he took it (but that was probably 10 yrs. ago). Good luck!