I seem to have fixed the humming problem. I really think it was the hard drive (later: weird as I typed the last sentence the hard drive started spinning loudly and I could hear the hum in my headphones so it's definitely the drive!). I have changed nothing. I am still using a cheap Labtec external mic on my Powerbook running 10.3.5. Would love it if others could post their hardware setup (exactly what model of mic (somebody posted a Radio Shack microphone model number but I couldn't find that here in Vancouver)? ) so we could all learn. Dave Slusher's software setup looks cool and definitive but nobody seems to be sharing exactly which mic they are using.