For converting wav files to mp3's I use Bladeenc, a freeware converter that is basically designed just to do that. It's a command line interface that looks like a DOS program, which gets us old DOSers sentimental--but it's really a 32-bit windows application. It does the job right, (and easily once you learn the default interface) is a very quick download, and doesn't do a bunch of things to invade your privacy and overload your system like the RealAudio products and other "jukebox" multi-function sound-file player/recorder/converter/managers.Death to bloatware! Bladeence rules!
Willie-O