I recently used DVD Audio Extractor to rip 48kHz audio from a concert DVD for listening to in the car.
DVD Audio Extractor was a huge help, but I found problems in the sound quality when I had it convert to 44.1kHz for burning on CD.
The problem showed up as annoying static-y glitches in the final CD I burned.
I resolved the problem by ripping to 48kHz WAV files, and then using Wavelab 4 to convert to 44.1kHz.
An expensive solution, I know. Perhaps there is a freeware/shareware converter that will work as well as this function of Wavelab?
Just a thought...