I've used audacity, Adobe SoundBoth, and Windows Sound Recorder
Windows Sound Recorder - It's a very light program and has some neat effects, but of course is is very limited, I use it when I need to record something quick and don't care about it's quality...
Audacity is cool and has tons of features like noise reduction, and some wacky effects, plus you can edit multiple tracks and blend them with fades, and it's free
Adobe sound booth has sequencial recording (can't remember if Audacity has them but I believe it does have) and is good for thos everyday sound tasks like cleaning audio or buping up the volume os a sound file and even cleaning some unwanted noises.
I've also used Wavepad but found it rather confuse in comparison to the above 3!
Also tryed Accoustica MP3 Audio Mixer wich is a decent MultiTrack Music editor =P
Have a nice Day