I've just reported about a guide to convert DVDs to your iPod from Engadget and here's another one from DAP Review.
I have seen this question pop up a few times, more so with the recent release of the new iPod video. So DAPreview.net whipped up a guide for you to help you through the process, since both companies seem to leave out of their instructions how to get DVD's onto their devices. While there might be other solutions then the one's shown in this how to, the software shown is completely free, with all the links need to download the software included. The software can also rip copy protected DVD's, though DAPreview insists that you only use your own legally owned DVD's.