what kind of error messages do you get from DVD Decrypter? You could just use DVD Shrink, and it will automatically burn with Nero when its done ripping.
To burn an ISO image with Nero Burning ROM, simply launch Nero, and close the 'New Compilation' window. Then select Recorder->Burn Image and select your ISO file to burn to DVD.
If you are using Nero Express, just launch Nero Express and select 'Disc Image or Saved Project'. Then be sure to select the option 'All Files' for file type, and then select your ISO file and burn to DVD.