Dolby 5.1

i was reading this article over on hd beat:

http://www.hdbeat.com/2006/01/24/espn-sportscenter-in-hd-and-5-1/

i have an hdtv and i get the hd sportscenter. how do i tap into the dolby 5.1 sound? i’m just using the built in speakers that came with my hdtv. so will the dolby 5.1 happen with the built in speakers? or do i need to go out and buy special audio equipment?

thanks