I know there are freeware ways of doing this but I have never been able to (easily) get good quality results from any of them (they tend to sound muffled for some reason although it may depend on the source audio). I'm sure it's user error and hopefully someone will post a good guide or something.
The few ways that pop out in my head (in order of quality/speed/ease):
1. The fastest results I've had are with Roxio Easy Media Creator 8 (and I would assume 9, the current version, works OK for this as well). There is a specific tool to extract DVD audio and make a CD out of it. In my experience this comes out sounding very good and doesn't take a lot of time. IMO the software is a bloated pig and is VERY buggy but this one specific tool works and if you need the functionality a lot more than makes the purchase worthwhile. I think Best Buy is selling this for $49 after rebate this week (CompUSA may as well if you want to order online). I seriously would not pay over $50 for it, there are PLENTY of deals if you can wait a couple of weeks if you can't find one. (keep an eye out)
2. You can use Total Recorder which (to me) is an indispensable tool. It costs like $13 but does have a trial. It basically installs a pass-through audio driver and can record pretty much any audio your computer can play. Just start up Total Recorder, tell it to record a WAV, and then play the DVD and it should produce a file that you can then burn to CD. (if you get choppy audio try another DVD playback program on your computer if possible, and if not, look for an option to turn accelerated audio/DirectSound off in your player's configuration). You can download the trial from highcriteria.com and see if it works for you (watch out, the trial is fully functional but it puts a short blast of loud static in every 60 seconds when it's in demo mode)
3. You could also record the DVD directly in your computer, if you have some sound editing software, and can configure your sound card correctly. Audacity would work for this. You need to set up your sound card's recording input to be "What you hear" (or similar option-- depending on the card/chipset it will be called something different). Basically, you need to pump the stereo mix of the sound back to the recording input. Pretty much any card can do that but the quality may vary. (free, though!)
4. You can always get the cables to hook up a (set top) DVD player's audio out to your computer's audio in and then just record in Audacity. I wouldn't recommend this unless you have a decent sound card since the audio inputs on most computers with built in sound are garbage... it will probably produce the lowest quality results but it's also probably the best fall back if nothing else works..