Forcing customers to upgrade their movie collections to new media formats is a great revenue model for the movie studios because they have opportunities to sell the same content to viewers over and over again. As a consumer, I don't want to be caught in that. I think that if you buy a movie once, you should be able to view it on different devices. You are still the only person that has possession of that content, and as long as you don't pirate that content and sell it or give it to friends, it's fine. If it's just for personal use, I see absolutely nothing wrong with ripping the same movie to multiple devices.
I also think the same should be true with books. If you bought a book at a bookstore and you want to read it on your laptop computer, I see nothing wrong with scanning the book, digitizing the pages and loading them on your computer so you can read it on the road. In fact, I've done this many times. Of course I've never shared these files with anyone, and I would never think of selling them, so I am actually protecting the intellectual property by keeping it to myself.
Yet publishers think that is breaking the law, and movie property owners also think it's breaking the law if you rip movies to other formats. With the legislative influence of the RIAA and the MPAA, it may turn out that if you ever record a movie you'll be arrested as a movie pirate and charged with a felony. It goes back to the classic Sony VHS recorder lawsuits decades ago. In fact, if Sony had won those lawsuits, then all VHS recorders would have been outlawed and people recording TV shows on VHS tapes would have been charged with piracy.
In my opinion you are doing nothing wrong if you own a movie on DVD and rip it to other player formats such as PlayStation portable, iPod video, cell phone video, or any other video format. Of course, if you go out and rent movies, and then rip them, then you are in fact doing something wrong, because you don't own that movie, you're just renting it. When you return the movie for rental, you should delete the files. In other words, you should only have those alternate files for as long as you have paid for the right to be in possession of the DVD. I think it's also unethical to buy a DVD, rip it, and then sell the DVD, because that shows your only purpose in buying the DVD was to borrow the movie so you could rip it. To be consistent, if you sell a DVD that you've ripped to a file, you should delete the file once the DVD leaves your possession.
Personally, I have a DVD collection that is always growing. I both own and rip that content, so I can watch the movies I own on other electronic devices. That way I can buy movies like "Oceans Eleven," which I think is a great film, and I can watch "Oceans Eleven" on my home DVD player or take it with me on a PSP or an iRiver, PMP, or other portable media device. If I ever sell that movie on DVD, I will delete those files. That's the honest way to handle it as a consumer. I'm supporting the movie studios by buying the DVDs, but I'm also allowing myself to be able to watch that DVD on a number of different devices that I own.
If you want to rip movies to other devices, you'd better do it now, because movie studios are pressuring Congress to pass laws outlawing any analog recording devices. In other words, you could be a felon just for pressing record on your VCR. That's what movie studios actually want and that's what they're proposing in current legislation. They don't want you to be able to record anything. A tape recorder will turn you into a felon if those laws become reality, and of course, you'll never be able to rip video to anything without breaking the law.
The intellectual property philosophies of organizations like Sony BMG are not only wrong, but dangerous. They are big brother intellectual property policies, where these companies would even install secret spyware on your computer, which is what Sony BMG did to millions of users without their knowledge, to prevent you from copying their music, meanwhile exposing your computer to hacker attacks. That's history, that's already been done. That's the way Sony BMG treats customers, and if we leave intellectual property laws up to the media giants like Sony, we'll all be branded criminals sooner or later.
So bottom line: Rip all the movies you want. Just make sure you own the DVD first, and don't share those movie rips with friends. But to protect your rights, fight against DRM (Digital Rights Management) schemes that force consumers to buy the same content over and over again for every new device or media format that comes along.
Want to stay informed about the fight against DRM? See DefectiveByDesign.org.