1) you want the most watts 2) the more speakers the better 3) get a sub-woofer 4) the more watts a sub-woofer has the more powerful it is basicly if you want the best, get a 7.1 sound system and look for the highest watts on the speakers and the subwoofer. it won't be cheap but it's the best sound.
I call BS on 7.1 I use a quality Crown amplifier and 2 pairs of Wharfedale speakers fed from a rather old professional Yamaha 32bit soundcard... I do lots of high quality audio and multimedia so sound quality is very important. These plastic pc subwoofer and transistor radio 2" speaker setups don't cut it at all..
i wasn't talking plastic, nor standard pc speakers. i'm talking of the works! 7.1 aren't cheap. also i said wattage and wattage is VERY important. obviously if the system is great the speakers will be great if the system isn't good the speaker's won't be good. that's where your 32bit sound card comes in handy. let me give you an example. my car has powerful bass just by it's system and speakers. it's a killer. doesn't have a subwoofer of it's own probably built into speakers. i dunno. the system produces ALOT of bass the car vibrates!!! now if i use my sony ericsson phone, it has a better sound system believe it or not and with the equalizers on the the car's equalizers off the car booms even more and the bass is much deeper and powerful. so when i say system is important you'd better believe it. you need a sound system/card before any speakers then the 7.1 is the best. remember...highest wattage!!!