Windows 7 comes with the ability play the sound inputed from the line in jack. This allows you to play a friends mp3 player through your computers speakers. This is especially useful if you have a laptop, as it means that it can be used as a portable speaker system. 1. Right click on the sound icon in the bottom right of the screen and select recording devices. 2. Select your line in device from the list and click properties.  3.Tick the "listen to this device" box then click ok and ok again. 
4. Finally plug the mp3 player in the the line-in socket using a 3.5mm male to 3.5mm male audio cable.  |