HandBrake is fantastic, but what if you need the DVD material for editing? I notice I've been asked this question more than once and since I couldn't find any simple guide online, I thought I'd write one down myself.
It used to be all about DropDV which by now seems to be discontinued. The best (most consistent, fast and with good image quality) is to use Apple's MPEG2 Component (20 EUR) and the fabulous MPEG Streamclip. There might be some commercial tools for this sort of thing, but this combo is powerful, fast and cheap.
Pop the disc in and in MPEG Streamclip, simply File > Open DVD, set the ranges you want to import and File > Export to DV. The default export options are fine for most cases. This method is really fast - about 2x realtime on a 2.4Ghz MBP using SD PAL material.
If you have to edit an RPC-locked disc, you should first rip the DVD to you HD using MTR, as you'll get a “File too short” error from MPEG SC otherwise.
And yes, this is all lossy-to-lossy, but sometimes it's the only way. With the tests I've made the quality loss isn't actually that bad.