sounds like a problem I just had. I had a dvd of tv episodes that was hybrid NTSC video and Film. I used telecide and decimate and it worked wonders. Actually I can't believe that someone wrote a dll complex enough to do this, but of course I'm a n00b.
Anyways search for decomb.dll and start with the telecide and decimate settings in the readme examples.
One of the examples converts up to video 30fps and the other 24fps. I found 24 fps to be superior, but my movie showed 70% progressive in DVD2AVI so .....24fps was much smoother
Hope this helps