Wow, I can't believe audiophiles are blowing off microphone quality as unimportant.
The Blue Snowball is only recommended because it's convenient and easy to use, a better set up would be a proper microphone with a mic preamp/interface, but that's going to be more money too.
I set up Ventrilo to use the best codecs available, so the mics aren't overkill at all.
VoIP compresses audio. Its like buying an HD800 to listen to low quality MP3s
To what extent depends on limitations, which in my case is upload bandwidth and friends. Audio quality never gets better than an average gsm call... Usually sounds something like a poorly mastered 48kbps mp3.
I think the Snowball works great for Youtube videos. http://www.youtube.com/watch?v=HsSk4qJ1Mb4
If your videos have an average of 10-100 views, might as well stick to a webcam anyways XD