First, you wouldn't expect the final product to be any better than the original. NeroVision normally does a fairly good job with the video and renders a viewable picture. Maybe the file you are using is causing problems for it.
Try posting your NeroHistory log and edit out your serial numbers.
You might be able to just give the properties of the files in question, and what burning settings are being used and perhaps someone might see what is wrong. The titles on the titles page will normally show what quality settings will be used during burning. The more specific information you can give, the better.