Sound Issue

Hello,

Id like some help with the audio in on macosx leopard?
At the moment iv got audio routed out of my Windows PC and coming into the Line In on my Mac. I have then got the output socket of my Mac going into my speakers. The problem is I cant hear anything my PC is playing through my Mac unless I run Logic or Garageband? The routing must be correct as it works in Logic and Garageband when I select the monitor.

This configuration works when I use Windows XP on my bootcamp partition but not on my Leopard.

Please help! Iv already looked under System Preferances and Sound ad the sound is coming through, I just cant hear anything.

Thanks a lot.

Ben Fox