From what I had heard the logitechs were superior, especially for the price difference, over the Creatives. However, I guess really this is all down to user taste. I'll be using it for movies, games and music, I hear (heh, no pun intended) the Z-5500s are over bassy and don't handle music well because of that.
http://cgi.ebay.co.uk/KLIPSCH-ProMed...QQcmdZViewItem <-Klipsch there, £160ish I believe + CRAZY (I understand they are big and heavy, but still..) postage cost (another £170 on top of that, and I guess i'd need a socket converter too if I were to import them)