What a great product! I have nothing but good things to say about Soundsoap. I use it to clean audio from interviews done with my digital recorder, and it does an amazing job! Copy the audio out of whatever you use to edit, import (.aif, .mp3, .wav, .mp4, .mov, .whatever), use the learn sound, and then tweek away at the knobs. You should be able to get good results in about 3 minutes. The "learn sound" function is key - and it helps to isolate 2-3 seconds of the sound in a seperate file, import it, learn it, save the settings, and then import the entire file you want to "soap". Great results and I've had no trouble saving as .aif and .wav.
Why not 5 stars? It's key that you use this product with other audio software (not as a plug-in necessarily, but so you can bump volume, isolate good sounds to learn, etc.) and the knobs and sliders give the software a sort of black-box feel - you're never really sure how it works. Finally, the instruction book is a .pdf file, which some people find convenient, but I find it a pain.
Again, I've used this for interviews with outdoor ambient noise (leaves rustling, water burbling) and with AC units, lights, refrigerators, fans, etc. running in the background. Don't expect this to take out certain voices, or interuptions in the background - it won't happen. It has to be constant, "broadband" noise.