hi dougyfresh,
I have X-Fi and have no problems with the card.
It's really nice one and no way I am ever going back to my Audigy 2 ZS.
Get it, try surround over headphones and you will know what I mean.
I have SIS chipset but read that some, not all, nForce4 mainboards may require BIOS update or X-Fi won't be properly recognized. Well, flashing bios is not a rocket science so you should be fine.
Once you installed the card, update the drivers. Latest one from last week does a great job and I did not see anyone complaining about it.
I wonder what ppl mean saying X-Fi doesn't have true digital sound. Sound is not digital as such, recording or playback can be and you can have either with X-Fi, can't see the problem with it.
X-Fi is a brilliant card. Interface is much better, more logical and better looking than with my previous Audigy 2 ZS . You can tweak sound as never before but you do not have to bother: default settings are, overall, fine. Crystallizer and surround sound over normal headphones work surprisingly well with music and games, respectively. And if you need more sophisticated controls switch to creation mode, this has them all.
Hope that helps