Sharing Speaker into notebook

Hi,
Does your PC have a sound system? If it is less than about 4 - 5 years old it probably has on board sound.
Rather than try and use the laptop's speakers buy a set of powered speakers, a cheap set cost less than $20, and would give far better reproduction than the laptop's speakers.
The only way I can think of connecting the PC's sound to the laptop is via line out ( requires sound system) in PC and line in on the laptop. Very inefficient and I suspect the connecting cable would almost cost as much as a set of speakers.