That's easy enough going directly to Creative's support site and selecting the version of Windows you are running and then scrolling the list of updates by date of release to end up seeing...
Downloads
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You have selected PCI Express Sound Blaster X-Fi Xtreme Audio and Windows XP.
To receive support for a different product, click here.
Sorry, no Creative updates are available for the selected query.
The original cd provided with the card will have the oldest drivers seen there.