the logitech z-5500 are awesome. i've got the older model the z-680 and apart from some cosmetic changes they're pretty much the same. my friend has the z-5500 and they don't sound different. The sound quality is literally amazing but a good sound card is needed to get the most out of them
Try and not get the x-fi, creative really are bad with their drivers. if i could do it all again i'd have gone for the auzentech or asus version of the x-fi...