when your soundcard matters...
Your soundcard has two basic functions. AD and DA conversion. When you are recording something, an AD conversion is taking place (or DD in the case where you are using a digital source with a digital card.)
On the other hand, when you are "playing" something through the audio card it is performing a DA conversion to prepare the digital signal for your apeakers or other analog equipment (unless, of course, you are using digital speakers.)
In any other case, such as saving frooty loops, your soundcard is not involved.
-Shaz