I'm not sure if you can get a clear answer to the legality question. Fair use seems to imply that it is legal to make, at the very least, personal copies for yourself of your own media for use or for backup. On the other hand, it seems to be illegal to break the DVD encryption scheme, which you have to do in order to make copies of DVDs into any format. I've heard so many 'professional' opinions on all this that I'm not sure who's got it right anymore. I'm definitely not an expert or a lawyer, however, so if I'm wrong somebody please correct me.
Here's what I know works for making personal copies if you're using OS X:
1. Rip the DVD to your hard drive using 0SEx. You can rip it as:
---a) a DVD image, which you can then mount later using Toast. No quality loss but also no extra compression so it takes up as much space as it does on the DVD -- usually around 8GB. If this is what you want to do you are done after this step.
---b) "Elem. streams" (zero quality loss audio and video files), which you can then convert (with quality loss) to mp4 files. (see Step 2)
---c) other options that I haven't found very useful.
2. If you choose "Elem. streams" you need to use tools like mAC3dec (for the audio) and mpeg2decX (for the video) to convert the audio and video to mp4 files. Then you can paste them together using quicktime pro.
Ripping DVD's losslessly isn't hard at all, but converting them to other formats like MP4 is still pretty messy on the Mac in my experience and unless you're willing to experiment and make a bunch of mistakes I probably wouldn't bother with it. There are sites out there that deal exclusively with this sort of thing. I can't remember any off the top of my head but a google search should turn them up if you're interested. Hopefully this will get you started though.
If you really want it to be easy, however, you've gotta get a PC.
Here's where you can get those tools: