I also bought a great mic (AT2020USB+) so that viewers were actually able to hear what I say. I went as far as recording the audio separately to avoid my notebook fan noise, keyboard clicks, etc. But I later figured that the high quality mic + Camtasia's noise removal are so great that I can save the (huge amount of) time and use the audio that I record on the go. (I was mainly recording 1-2 minute how-to videos.) Now recording a 1 minute video takes me ~an hour instead of a day that it took at the start.