I read a post recently about how to get DVDs onto your iPhone. There must have been twenty steps, and I don't know if the software was free, or required a purchase. I think I've found better software, and less steps to do it. It is not a 'quick' process, maybe my computer sucks. Any ways, here's the approach I'm using, and all the software is free.

Download Software
DVD Decrypter (DVD Ripping Software)
Videora (Video Encoding Software)

Step 1.
Open DVD Decrypter

Click the stream processing tab, and check the video checkbox, and the 2ch English checkbox. This will get just the movie and audio. Then click on the destination folder at the bottom, and choose a location to save the file to. It will create a .VOB file. This file is what you'll encode in Videora. Now just click the DVD > Hard Drive image at the bottom, and wait... and wait... and wait.

Once the ripping is done, you can close DVD Decrypter. 

Step 2.
Open Videora

Click on the settings menu option and configure it to work with the iPhone screen. You'll only need to do this step once.

 Click on the Convert menu option at the top, and then Video Wizard, locate the file on your machine and click the 'next' arrow. Steps are highlighted below.

Next, select your video settings. You'll need to play with these to determine what you preferences are.

Finally, click the Start Converting button and wait... wait... wait....

Then, to get it on your iPhone, simply import the file Videora generates into iTunes, and then choose to sync it to your iPhone. So I have a process that is roughly seven steps to get just about any DVD onto your iPhone. The article I read was 19 steps, I didn't have the patience to read the entire thing, yet alone try it!

The videora UI is horrific. Lots of ads, but nothing shady gets installed. I like it because it's free, and simple. You can rip to other devices too like PSP, iPod video, and other formats. Give it a shot and let me know how it goes.