CS - she's got a lovely voice, but that's exactly the recording quality I want to avoid: that constant background whirr makes it unlistenable to me.

Matt - yes, just voice. Not sure about this EQing of which you speak - the big problem I'm getting is general ambient white noise, which appears on the waveform as a thick fuzzy line where there should be a thin line of silence. Audacity's noise reduction filter sorts that out, but seems to do it by nuking those frequencies throughout... & hence making me sound like I'm singing in a box (and through my nose, although that may just be because I am singing through my nose!).

I've tried GarageBand, but I actually preferred the quality I got recording with Audacity. GB has a 'gate' setting for on-the-fly noise reduction, but it didn't seem to do much.