If I were you, I would rip DVDs using the AppleTV preset.
You may get a larger file size, but it will be more like DVD quality and will prevent you from having to back and rerip all your DVDs in the future if you want better quality (or if you get an AppleTV).
Just put a DVD in, select the source in Finder when it pops up automatically, select the AppleTV preset, then push Start.
You should then see a file on your Desktop, which you can then name and add artwork. After that, just drag and drop into iTunes.
Trust me, the AppleTV preset will look much better if you ever plan on watching any of the ripped movies on a screen bigger than the iPhone.
Remember, it is easier to convert down, not up.