"Rippin" a DVD IS illegal if the disc has CSS which almost all commercial releases have. Period. You are circumventing the digital copy protection which is illegal under the Digital Millenium Copyright Act whether you bought it or even if you created the disc yourself and put digital copy protection on it yourself. Is it logical or right? Doesn't matter, it's the law now. "Fair Use"? No such thing anymore if the content has any kind of digital rights management. I don't back the law, but that's the deal.
Ripping the DVD is only the first step to getting to a PSP. You will need other software to recompress it to the PSP format which isn't MPEG2 like DVDs. Then you will need to put in on a memory stick ($200 for 2gigs). So, you didn't spend $0, but $200, you technically broke the law, you have a copy that you'll need to erase if you want to watch something else, you spent a crap ton of time on it, you wound up with a recompressed copy since DVDs are already compressed and you don't have any of the bonus materials, so Boohooo, not booya.