I don't know if I'd agree with BDCPUAH about the Marine guide being a photo copy of the Arco book. I had both to study for the ASTB with, and they were as different as could be. I only missed two on the Mech. section and I know it was the Marine guide and not the Arco book that made the difference. Basically the the only thing the Arco book is good for is the spatial section of the test.
Rhollin1, I know where you're comming from about retaking the test. I have pretty ok scores, but like ghost said, slots are hard to come by these days. I have a 6 AQR, 7, PFAR, 5 FOFAR, and a 53 OAR. I've been told by more than a few people that a year ago I'd have been accepted ASAP with those scores. If you're going for supply, do they only look at your OAR? If so, I can tell you that the math and mech. sections are the ones that count for that score. Bust ass reviewing for those sections if you decide to retest and you'll see your OAR shoot up.
C