When you use DVD Decrypter in IFO mode it strips out the movie files but they are not in a DVD format.
Running DVD2One creates the files for DVD format so that, for example, Nero recognises the files as a DVD movie.
Try using DVDShrink,
www.dvdshrink.org, it's freeware, and it rips and shrinks at the same time. The resulting files can then be burnt by Nero.
Make sure you are using an up to date copy of Nero. Earlier versions didn't create a "true" DVD and couldn't be played in all DVD players. Later editions have overcome this.
Hope this helps.