I've got access to three different discs, the Avia guide, the Sound and Vision HT tune-up (also by Ovation) and DV essentials.
They are all good, and there's quite a bit of overlap. Avia is basically a more advanced version of S&V HT tune-up, so if you're not super technical and don't need all the extra tones/patterns etc, go for that. The S&V disk was the only one to have the cool extra Dolby demo's (I think). Also the S&V tune-up disk is a little cheesy in my opinion. The DVE disk is great if you're not super technical and offers good coverage of, well...the essentials. They're all 3 good and depending on how technical you want to get, any will suffice. You can find them for fairly cheap if you look around online...
later...