Pardon me if you've heard this before, but: why not simply use iTunes to convert your WAVs to MP3s? It's free, it's available for Windows or Mac, and it will do a batch of files, unattended.

Just make a playlist, set iTunes's preferences [Advanced: Import] to the MP3 settings you prefer, then select all files in the list and right-click. Choose "Convert to MP3".

The new MP3 files will be added to the main iTunes Library, the master list of all your iTunes tracks. From the Library, you can drag them, or, right-click a file and choose "Show Song File".

You can choose bit rate, sample rate, VBR/CBR, stereo mode, channels, filter frequencies below 10Hz, and set a quality setting, from low to highest.

Just one install, no configuration.