There's a choice of bitrates in Nero's encoder, up to 96/high quality, which produces pretty good results.

Don't know of any free standing progs - Thompson presumably produce one, since they put out a freebie limited to 64 kbs some time ago. Steinbergs My MP3 Pro sounds promising, but I can't get the mp3 checkbox to function. I think it's MP3 Pro rather than mp3pro, if you see what I mean.