In many people's opinion LAME is currently the best mp3 encoder. Check it out at
the LAME Home Page. I'm not certain it will work with Audio Grabber but it is available as a .dll and an executable, so chances are good it will work. If not (or if you want to try something different) get
CDEX, which is a ripper/encoder just like Audio Grabber. LAME and CDEX are both freeware, by the way. If you use LAME, do Variable Bit Rate V4 or higher and use Joint Stereo. The mp3's that result sound excellent, even on high-quality stereo equipment.