Had I found this earlier, I would have added it to my Zune hacks post. With this registry hack, you can enable playback of your Zune over your laptop's speakers. First of all: warning - don't edit your registry if you don't know...oh blah, blah, blah...you know the drill.
1. Add the following key to your registry, either by creating a reg file with the text, or go there yourself and create the binary value:
3. Enable the input monitor by going to "Control Panel" --> "Sound" --> "Speakers/Headphones." Click on "Properties," then click on the "Levels" tab and enable the input monitor button.
4. You're done - rock out!