While I concur on the ATP3's as being the best bang for the buck under $100, I'd have to say listen to the Klipsch Promedia's and the Logitech series in the same wattage range. The promedia series is getting a run for it's money with the Logitech Z-680's and the 4.1 which escapes my mind for th emodel number, which is bad, cause I own them

(400 watt 4.1 THX, Z-580 maybe? Not sure.)
Side by side, I personally think the Logitech are better, the major factor in this opinion is, that I work at a store that sells both, and the Klipsch break constantly, if not from bad amplifiers, then from the serial controller input on the back for the control box (Volume, bass, etc), the prongs are not soldered in well and the smallest jiggle can start making them pop out of their socket and get stuck in the sub's input, hence no more working speakers, the prong problem I have seen on 5 sets, so far personally, the amplifier problem only on 2, but its been widely acknowledged. Another thing is Logitech's have bananna plugs in the back, you can use better wiring or the plug option for that matter, klipsch has this dinky propriatary cable system.
Don't get me wrong, they sound great, but the Logitech's are a bit cheaper, and build quality is better in my view. But thats just me, both are great systems. Altec is the best for under $100, the ATP3's have been awesome and been around for about 2-3 years now.
Hope that helps.
PlaceofDis said:
secondly if you want the absolute best for speakers i have heard that Kilipsh is the best...i might be spelling that wrong so sorry, but take a look around on the forums and you will find a couple of other threads on the topic of speakers
However, if you are on a budget then i would personally reccomend to you Altec Lansing's ATP3 2.1 speakers, they are the best bang for your buck, excellent sound quality for about 50 bucks...