Sound Forge is expensive professional level software that is very good at what it is designed to do - edit audio. I think it is sometimes bundled with CD Architect - Again, very good professional level software that is good at what is is designed to do - master audio CDs. Nero, on the other hand is not professional software and it trys to do all things. It is OK at most, but for editing audio files / mastering CDs SF / CD Architect are much better.
You may want to check out Sony Forge Audio, it is a stripped down version of Sound Forge. I have seen the for free after rebate.