|welll.... you can hook multiple speakers up in parallel if you wish... but it will still be stereo... just through more speakers that's all.|
You will need an external sound card if you want real DD5.1 sound. An excellent choice for a laptop is the Audigy 2 ZS video editor. It's an all-in-one device.. audio in/outs, video in/outs, 5.1 sound, 4 port usb hub, firewire connect, and a few more things. The neat part is that it hooks up with one simple usb cable.
Here's a link: