Audiograbber is freeware and you control what bitrate you want.
It needs a third-party codec to operate, but one is available (LAME) on the same site:
http://www.audiograbber.com-us.net/download.html
Note that MP3(and for images, JPEG/GIF) is LOSSY compression, meaning information is removed and can not be retreived = loss in audio quality. The lower the bitrate the worse the quality.
Programs like WinZip are LOSSLESS compression and therefore have lower compression ratio's.