not being bias or what, but creative was never good at speakers.

the megawork 550 is ok, but the woofer bottoms out when the volume goes beyond midpoint.

for logitech, their system are either just loud, or too bass heavy.
there are alot of ppl who say that the Z5500 is good, but i think not.
its satellite speaker are very good in its class, but the letdown is that the woofer is only strong when pushed beyond a certain volume. below that, the system is just loud and boring, lacking low end support.

just my two cents ppl. =)