Princeton Review/GRE: correlation between scores

To those of you who have already taken the GRE - how well did your real score correlate with your practice exam scores? I've done very well on the few I've taken so far (>1250), so I think I'm ready to take the exam. I'm just a little afraid of getting a surprise when I walk into the real GRE. I also have the Barron's prep book, it only has one practice CAT GRE and I haven't taken it yet. Thanks in advance!