For HIFI Music playback and recording,EMU 0404 is much better than rest of soundcards you listed.
For Home Entertainment(e.g watch movies),X-Fi Xtreme Audio and Digital Music SX are better than EMU 0404.
M-Audio Audiophile2496 also a good choice for music recording and playback,price is more or less same as 0404.
Which one you wanna pick up?it depends on your needs.If you like music and recording,you can choose 0404 or m-audio2496, If you like watch movie,you should choose X-Fi, because if you are using professional soundcard to play movie, the sound also like crap
