Had been trying to work out how to put dvds onto PSP when I came across this simple video that takes you step by step and shows you exatly what software you need, and how to use it, (with the PSP in mind). I tried it with Monsters Inc. and it worked first time. Very easy to follow. Especially good for someone like me with limited pc knowledge/expertise. File came to 450MB. Which was lucky as my Sandisk 512MB card only holds 467MB in reality.
http://psp.turbosweet.com/_files/tutorials/dvd_to_psp/dvdpsp.htm