I use Logitech Z-560's. 4.1 surround, $200 back in March of '03, now they're probably $100-150. 400 watts total power (188w to the sub; 53w to each satellite). Let's just say coupled with a SB Audigy 2 ZS, this thing pounds, and that is an understatement. Then, if you go so far as to crank up the bass knob, turn up the volume, go into windows sound properties and move the Bass slider up as well, you'll be bass'd to death...literally.
Anyway, I've had these speakers since March of 2003 and I love them.
I must add that if you're going to use any type of high performance or amplified speakers, you'd be best off if you get a better sound card (preferably Audigy) for your laptop, the onboard sigmatel makes the speakers (at least mine anyway) sound really bad. The onboard is good for headphones, but as soon as you get a high performance system, you will hear a ton and a half of background noise, fuzz, and such.