i have some logitech z640's (i think thats what they are called?) they are actually pretty good considering the size of the subwoofer. i bought them off a friend for like 30 or 40 bucks. the small sattelite sppeakers that were with it arent that great, so i used my stereo speakers instead.
I have my Yamaha System hooked up to my computer, so I guess you can say its pretty sweet when I get to playing music in the house. Its two Main Towers, 6 mounted Surround Sound Speakers and a 15" Sub: