I noise reduce my films a lot. I use Noise Reduction in Audacity (Mac) or Cooledit (Win), at the lowest setting, and create a new noise-reduced WAV. Sometimes I noise reduce twice and save it again also. The result tends to sound very electronic. However it will sound better when you mix your one or two noise reduced tracks together (in Premiere or FCP) with the original not noise-reduced WAV (added in at a lower volume of your choosing). Also, on the noise reduced version you can lower the volume to nothing on very quiet parts of the audio, which tend to sound more electronic than when people are talking loudly.

The results of this in my movie Gods of Los Angeles were quite good overall.