Amazon is selling the Logitech Surround Sound Speakers Z506 for only $58 shipped, originally priced at $99.99. Just “plug in your entertainment gear and you can immerse yourself in big 5.1 surround sound – even from your 2-channel stereo music, movie and game tracks.” Product page. Video after the break.
The speakers also convert simple 2-channel stereo (like your old video games and CDs) into immersive surround sound. You’ve got 75 watts (RMS), enough to fill the room with window-rattling sound.