When you register for the GRE, the ETS sends you a CD with two sample tests. Do those tests and you're good to go. IF you really really feel you need more practice, I hear Princeton Review's book is pretty good.
But really, doing those two practice tests should be enough. It's not a very difficult test, and if you just go in with a clear mind you'll do fine. Er, your brother.
Also, dont buy books for the word lists. Type in GRE word list in google and there are tons of sites with free word lists and whatnot.
Cheers
Captjack