Recording: 1 Mic + PC Sound to different Tracks

You want the Snowball on one track and sounds that the computer plays on another? Audacity cannot this, but there is another free program that can - Kristal Audio Engine.
http://www.kreatives.org/kristal/
There is one limitation, though, you’ll not be able to listen to the sound from the microphone as you record. Kristal is a good recorder, but has limited editing capacity, so record with Kristal and edit in Audacity.
We had a thread not long ago discussing your situation. Recording mic/stereo mix at the same time

Koz speaks the truth. No speakers, everyone should use headphones.

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Ragnar