Apparently from what I've been reading, the X-FI functionality is software only. There is no dedicated X-FI chip, so it can't really be considered as a true X-FI card.
It runs off Soundmax drivers.
Try downloading the drivers from the Audio section. I don't know if your Windows would be 32bit or 64bit, but you can choose that from the drop down
I hope this solves the issue.
It is meant to be a replacement for an on-board chip, but as a riser instead. So it should offer sound functionality. That I'm not 100% certain of however
Hmm but you may be right. It's meant to go into the black slot on the Asus motherboard, so it may only work with that specific make of motherboard