I've recently bought the Liteon LVW-5005 Home DVD Recorder and have been experimenting along the same lines, as I want to be able to backup/copy old VHS recordings of my family once transferred to DVD.
I made a test recording of random stuff from the TV and then used Sonic RecordNow (came with my Liteon PC DVD burner - part of Sonic MyDVD), to make a Global Image onto my HD. I was then able to burn this image to another DVD - worked fine.
I haven't tried doing this with Nero as yet.
You may find these links helpful.