Creative Extigy and what speakers?

Well im planning on buying a Creative extigy for my laptop (i only have USB 1.1) and im unsure of what speakers to buy. I preferable want Creative speakers.

Ive been looking at these speakers:
Cambridge SoundWorks® MegaWorks® THX® 5.1 550
Creative® Inspire™ P580

How much better are the first speakers? I know the extigy is pritty old so will the extigy be able to deliver the goods as it were, for the megaworks 550? Oh and are both of the speakers compatible with the extigy?

Can anyone else suggest any other speakers?

Thanks,

Adam.