If you're looking for an easy way to get audio from your laptop to your sound system, take a look at the Oono Transmita. The unit comes with two pieces, one to plug into a headphone/line-out jack on your laptop or digital audio player, the other to plug into your line in on your stereo.
The wireless works on the 2.4GHz band, the same band as your WiFi and some cordless phones, and has a range of up to 50 meters (164 feet). The range is most likely less if you go through walls, but should be enough for transmitting audio from room to room.
The Transmita costs 34.99 ($64) and comes with "2.4G wireless stereo dongle and receiver, 2 power adaptor sets, a USB cable, and 2 audio cables."