I read the Adversary Cycle, and a few of the RJ books back in 2005, but now there are revised books, and I want to reread those six books as well as everything I haven't read. I'm wondering if there's much difference in the revised editions or if I can stick with the old editions. This is the difference of getting the books from the library or spending money I don't really have for the books on Amazon.
Another thing. I put the first book of the prequel trilogy on hold from the library after reading The Keep over the weekend. I'm assuming this is a good place to start with Jack, but I might be wrong. Can anyone tell me? Thanks.

The Early Years trilogy works better, I think, if you come to it after you've read the rest of the series. You the reader know so much more than Jack and realize what parts these other characters he meets will play in his future. They're different from the main series in that they're dark, gritty crime novels.

The Tomb and The Touch were revised to cut them loose from the 1980s but aren't substantively different. Nightworld, however...you'll need the 2012 edition.