I find Audacity as good as a few commercial products I've tried. Of course, each product has its strong and weak points, but Audacity ranks up there with the better ones - and the price is right.
PG Music's Power Track's Pro Audio is also good and inexpensive. It has some different effects and editing tools and isn't very expensive (note: although I write after-market style and song disks for PG Music's Band-in-a-Box program, I have no professional affiation with them).
Insights and incites by Notes
Bob "Notes" Norton
Owner Norton Music http://www.nortonmusic.com
The Sophisticats http://www.s-cats.com