My scores were as follows:
Power Prep AVG: 768V/763Q
Actual GRE: 670V/800Q
In my opinion, pretty good indicator but just like everything else, its not perfect. I will say I had a very bad episode on my second Powerprep test, I scored a 660V/630Q and I wigged out a bit, but I rushed through that particular test because I had just wrapped up the NOVA math prep and I was chomping at the bits. My advice is go slow and pay attention especially on the quant., I scored really high by taking my time and guessing on the last 6 or 7; much higher in fact than rushing and not checking my work with the intent of finishing the test with time remaining.
The Quant seemed about the same level of difficulty as the Powerprep. The verbal was much harder but I think its all about the luck of the draw.
John is correct, Kaplan, 800score, etc. all score you lower especially on the quantitative. 800score is a really difficult test to finish in 45 min., but not really a difficult test in and of itself. My advice is to use it but don't try to finish it in 45 min. unless you are Max Planck's great grandson. Also try the Manhattan GRE online test for practice but again don't put too much stock into the time limit.
Good Luck!
