I think there is a much newer Creative USB soundcard than the Extigy, maybe an Audigy model, and there is also a Turtle Beach one.
Go to Newegg.com and look for USB soundcards.
I think the original Extigy was USB 1.0 not 2, and had some problems with sound dropouts. I don't know if they ever fixed that or just moved on to a new model.