Well, ok it doesnt actually convert to .wav, but it records the sound created by MIDIs. For example, im playing my midi in the background. Before I play them, I start recording the sound, and bam, by the time it's done, im done, and I have a .wav copy of a .mid!
THE FILE COMES WITH A TEXT DOCUMENT. READ IT OR YOU CANNOT USE PROGRAM PROPERLY!
Download the program here