When I started GMAT studying, Kaplan 2006 was the first book I bought, and my first CAT program. I started off pretty badly but broke 600 by the time I finished Kaplan. Then I took Princeton Review, (which I found awesome) and got around the 650s. Then I used powerprep and Kaplan 800 to score 680-720. I scored 660 on the actual exam and I’m definitely retaking it. I have found no decent books besides Kaplan 06, Kaplan 800, and Princeton.
ARCO was a huge dissapointment – the edition has rampant errors in its problems and is worded badly. The CAT CD was even worse.
Barron’s 13th edition was a complete ripoff – the CAT program is from 1998 and is about as user-friendly as.. something that isn’t very user-friendly.
I think the best program is ETS’s free powerprep, but I would advise that you only use it in your final study stages. It’s not for studying as much as for accurately estimating your score. When I took my GMAT, the format was exactly like powerprep. Frankly I’m shocked that none of the companies use the format.
One part you have to remember is that on the actual exam – you will probably be putting effort into the AWA section, which is hard to get psyched about during practice. I underestimated how scared I got on this section and was a little exhaused after the two essays. I then got 48 quant, which was ok, but by the time I was at verbal, I was literally nodding off and scored 33. Remember – you can’t bring coffee in!