Audacity sounds as good as software costing hundreds of dollars (this is more about your microphone than software). It processes audio at professional sample and bit rates, and can turn out a professional sounding podcast with intros and music beds. It lacks looping for music beds, but if you are not planning on creating custom music for your podcast, you won't miss the absence of these features.
Sorry, Windows users, but GarageBand is only for Macs, which is a shame, because it strikes a near perfect balance between power and intuitiveness.
In addition to the audio capabilities of Audacity, Garageband adds a fantastic library of music loops you can join together to create custom music for your Podcast. If you want to get fancy, some of these loops contain virtual instruments which can be modified so that you can write your own melodies and beats.
GarageBand is targeted for musicians, but it contains all of the capabilities needed for producing the most complex, scripted podcasts. If you're lucky enough to own one of the newer Macs, just plug in a USB microphone,and you're literally ready to go!
3. Sony Acid Xpress
Acid Xpress is a free, limited version of Sony's Acid Music Studio software. It can record and edit audio, and emulates the looping capability of GarageBand in a free software for Windows.
Acid loops are royalty free music that can be stretched to fit different tempos and keys. Acid XPress comes with a few trial loops, but you will either have to buy a library CD ($30-$50), or download free loops from the internet if you want to use its soundtrack capabilities.
Work can be done in XPress, but the limited track count, disabled effects, and annoying pop ups mean most people who like the Acid workspace will opt to move up to Acid Music Studio ($59.95) Acid Xpress is simple to learn, so you can quickly get up and running.
4. Pro Tools LE
Pro Tools LE is for established podcasters who are looking to expand into a powerful and deep software. Pro Tools LE ($300.00 and up) has all of the features mentioned in the other software listed. However, the biggest reason to own Pro Tools is that most any professional studio are bound to have a copy running.
Something important to note is that Pro Tools only runs on specific Pro Tools rated hardware. To me, Pro Tools is a high end product with loads of features and power, but not essential for the first time podcaster. File this under “Nice to have if you can get it,” but be warned: along with tons of features comes a bigger learning curve.