Hi Dale,
If you can hear the .mid file when you play it in Midinotate and Windows Media Player, this suggests either that MP3 Maker doesn't work or there is a setting that needs adjustment.
As Clyde suggests, midi needs to be recorded rather than "converted." Perhaps MP3 Maker does this and calls it conversion. I am not familiar with the product or how one sets it.
Audacity is a good way to get the .mp3 file, as Clyde also suggests. Record it there and you can save it to whatever format you want.
Synthfont (
www.synthfont.com) sounds a bit more like MP3 Maker,in that you load the .mid file then play it, saving it to an .mp3, .wav, or whatever, file. Synthfont does the playing and saving; it's the only program you need open at that point.
Good luck,
mgj