Practice CAT that gives the best prediction?

[cheburashka]

For those of you who have already taken the GRE and have studied from multiple books w/CDs/online, which one had the practice CAT that gave you the score closest to your actual GRE score later? I have taken two CAT from different sources, and the scores I got were VASTLY different. I'm trying to gauge how I'm doing, but now I'm not sure what to think!

I'm studying from Kaplan, PowerPrep, and Barron's. I'm guessing it's PowerPrep, but then again it doesn't seem like their stuff has been updated all that recently.

Thanks!

[Eigen]

When I took it last year, my PowerPrep score was pretty close to my real score.