Cool Edit Pro 2.1
Cool Edit Pro 2.1 is definitely the most popular sound-editor for Windows
Incredibly detailed comparison chart of best 3 Sound Editors: Sound Forge 7+8!, Wavelab 5 and Adobe Audition 1.5
Note-16.3.2006: Syntrillium Software got bought by Adobe. Cool Edit Pro 2.1 became Adobe Audition 1.0. Here's a detailed review of the latest version Adobe Audition 2.0.
The shareware program Cool Edit became the most popular stereo editor for the windows community. Probably because it has a nice interface that is really easy to handle, and many built in audio effects.
The "PRO" version also became a multitrack recorder, which some people need and others not. You can not only mix in stereo but also in 5.1 surround format.
In version 2.1 it offers more than 45 DSP effects, supports 24/96, scripting and batch processing, and reads and writes more than 20 file formats, including MP3 encode and decode.
You can use it as Stereo Editor or Multitrack recording software. In version 2.1 you can even perform 5.1 surround mixes.
I think it's a really nice stereo editor and a good multitrack recording software if you mainly record real instruments by overdubbing.