I've recently converted a dixv-encoded film to DVD using Nero 7. The film is of OK quality, not great, just a bit soft in the lines. But after conversion, whenever something in the scene moves quickly it leaves a trail of lines after it. Almost like it can't keep up. I chose the aspect ratio, but left the other settings on automatic. It does this on both a DVD-Rom, DVD-RW and a stand-Alone DVD player. Any clues???
Try another conversion app to see if that helps. WinAVI Video Converter and DivXToDVD are a couple that come to mind. The WinAVI has a logo on the screen till purchased, but you can see if it works before buying.