I have the powerscore CR bible..it's a GREAT book. I used to get about 40% of all the CR questions wrong on my practice CATS, but after I went thru this book, my CR % of error was significantly reduced - right now I get about 5-10% of the CR questions wrong on the CAT, and I'm still working on improving it.. good luck.
Manhattan GMAT Adapative CAT (Taken Jan. 19, 09): 600 (Q-42, V-32)
Manhattan GMAT Adapative CAT (Taken Feb. 14, 09): 620 (Q-43, V-32)
GMATPrep CAT (Taken Feb 28, 09): 590 (Q-39, V-34)
Manhattan GMAT Adaptive CAT (Taken March 6, 09): 640 (Q-44, V-34)
800Score CAT (Taken March 14, 09): 630 (Q-41, V-36)
800score CAT (Taken March 20, 09): 600 (Q-41, V-31)
Manhattan GMAT Adaptive CAT (Taken March 22, 09): 600 (Q-39, V-34)
GMATPrep CAT (Taken March 28, 09): 570 (Q-37, V-31)
Knewton Diagnostic CAT (Taken April 3, 09): 640 (Q-45, V-33)