You need to output the Pinnacle project as a set of DVD files instead of burning. It's possibly an option in the dialog when you are setting up the burn in Pinnacle. Just direct it to a folder on your hard drive and it'll place the files there instead of burning them.
After that, open Nero, (NOT Nerovision), and select a DVD video compilation. Drop those same files into the compilation and burn away. If you open the files in NeroVision, it will re-encode them again, and you don't want that.