One of the best things about the Zoom, Edirol or similar is that it's portable so you can take it to the best room for recording in (for a start, that's not any room with a computer running in it) and place the mic in the best position. That's the factor that makes the most difference to the sound, and the quality of the mics in a Zoom H2 are quite good enough to make very good recordings.

If you need to use Audacity's noise reduction on a fresh recording, you are recording it wrong. That should never be necessary - find a quiet place!

For something that's going to be turned into MP3s and uploaded to the web, you don't need 24 bits - 16 bits is CD quality already and the next step to improve your sound (which nobody does at home) is to spend a fortune on acoustic treatment. Then maybe mics...

Anahata