This app works great. I was using it for my Portable Media Center and loved it. And it works perfectly for the Zune, too.
Here's the bonus -- you can rip DVDs for larger screen size than the PMC/Zune. "Why would I want to do this?" you may ask.
Well, I have them saved in my Shared Videos location on my MCE PC and when I fire up the Xbox 360, I now have all those movies listed and viewable in my living room. Are they HD? No. But, they really really look good. They passed the wife approval test when I turned on Nanny McPhee for the kids and they all thought we were watching the DVD.
This app is a must for any portable video wanting person and if you happen to have Netflix, well, more power to you.
Not that I condone that.
P.S. I've tried Mayakama's (spelling?) app for this purpose and really prefer PQ DVD. You can try both with a trial and I think you'll find the UI on PQ DVD to be much better and more functional.