that probably isn't going to work, i'm afraid.
most likely, the GD DVD has DTS or AC3 as the audio format. this will mean you are s.o.l. on that route. what you CAN do, though, is rip the entire DVD to your HDD. Once there, you can split (de-mux) the audio from the whole thing. Then you can convert it from whatever it is to wav.
This is doable all with freeware, but it takes a bit to get it right. Most of the technology is gleaned from the real DVD hacker guys, like the dudes selling the Chinese version of the Matrix on eBay or something.
If you really want some more info, let me know. And the first place to start with DVD stuff is always Doom9.org.
-UJ