Audigy's XP drivers work flawlessly for me.
I know people tend to be brand loyal. And I'm assuming the people talking about the "comparisons" are basing their opinions in blind faith for a particular brand (or blind scorn for another). As I said before, Creative has long been, in my opinion, one of the least reliable hardware developers. Their products have had spotty performance, and the driver support has been awful.
But I upgraded two computers from the Santa Cruz to the Audigy, and noticed a marked improvement in both. With the Audigy, they finally got it right. For a long time, the santa cruz was half the cost of the audigy. Now, they're about the same -- I bought three audigys from TCWO when they had their $55 anandtech special. My current two cards are being used with the Logitech Z-560s, and the sound is fantastic. I wouldn't say it's overall "dramatically" better than the Turtle Beach, since the TB sounded great too. But the performance in games is noticably better. You can max out all audio effects, and there IS a dramatic difference in the way they sound.
Play Wolfenstein on a Turtle Beach, adn then play it on an Audigy. You'll absolutely hear the difference.