I do myselfe got a Creative X-Fi Extreme Music that I have removed from my because there was no support at all for it in Linux. For that solely blame Creative.
They do themselves release drivers for X-fi cards. But only the more expensive ones, and only for 64-bit operating systems. This to me seems increadibly stupid but that's only my opinion. I suppose it validates the higher price on the more expensive card from their point of view.
But I'm now wondering. Has there been any progress on that front since I last did my research around the net about a year ago. I do know things can happen really fast in the world of Linux so I'm hopeful. Are there any drivers, open or close sourced, that can make my Creative X-Fi card squeze out some sound?