John,
I think headphone out to mic in on the pc is the worst of both worlds.
Headphone jacks usually have lower output than the speaker output so you
don't blow out your ears. It might be possible to increase the level on
the mic input to get more into the soundcard, but I think you would be
much better off using a line in. The headphone jack may work much
better going into a line in. I think most guys use speaker out or get
audio from an accesory jack that offers a line level audio output.
Have fun, Steve KW3A