They all basicly have the same price, but wich one would be the best choice? As long as it has a good subwoofer.

Logitech Z-3l, 2.1, 40W RMS

Logitech Speaker X-620 6.1 70W RMS 1285.- (I have a 5.1 motherboard, these speakers are 6.1 , can I still get them to work?)

Logitech Z-3e, 2.1, 40W RMS

Logitech Z-540 4.1 40W RMS

oh and dont let the W's trick you, they are known to make A LOT of bass for a mere 20W