This is the simple way I record just an interview with another person. I use Skype and Audio Hijack Pro ( http://www.rogueamoeba.com/audiohijackpro ) on OSX. This gives me two track files each with it’s own custom preprocessing filters. That reduces work in post edit. Also makes it easy to do later processing on each person without affecting the other.
I wanted to play around with sending video to YouTube. So I put together a few minutes on how I do noise reduction using soundtrack pro for podcast tracks. I use a combination of soundsoap (http://www.bias-inc.com/products/soundsoap2/) and the built in noise reduction in Soundtrack Pro. Alternatively instead of soundsoap another even better and of course more expensive noise reduction plugin is MR Noise (http://wavearts.com/products/plugins/mr-noise/)