Hi, Racer - a couple of months ago, I needed the trumpet tune "El Nino Perdido" for a play, and had to follow it with the sound of angry bees. I transcribed the tune onto Noteworthy Recorder and made a MIDI, and then used the Windows Sound Recorder and recorded a WAV from the MIDI (I added a little reverb to make the trumpet sound more credible). I set Windows Media Player so it would open a new window for every WAV file I clicked on, and then I could play several sounds at once and adjust the level of each separately. I recorded from the computer's line out jack to a cassette recorder, but I could have recorded onto a CD just as easily.
That was the first time I mixed sound effects on a computer, and it worked very well - and it was a lot easier than any method I've tried before.
-Joe Offer-