You can use Nero Vision to do this conversion since you already have it. ConvertXtoDVD is another popular commercial product for this conversion.
There are also some free choices, including AVStoDVD, DVDFlick and FAVC.
What are you using to play the converted files? You might try VLC media player...it is free to download and use, and it supports dvd-video. www.videolan.org
If your dvd player can support avi files, you might not have to convert at all. Especially if these are avi files encoded with divx or xvid codecs. Assuming your dvd player can use avi files, all you would have to do would be to burn to a dvd as data files.