I think there should be a gameport->USB adapter around. There is AnythingtoUSB so this should exist as well 😀
So a quick glance at ebay (seach gameport usb) does reveal a couple of those, the price around US $6.00 (some less some more).
Probably cheaper to get one of those than to find the X-Fi adapter if one exists.

Most of the ones I've done research on say that they won't support Microsoft's force feedback joysticks...and are in excess of $15-$20. I'm hesitant to use eBay at this point, due to poor luck with game controller hardware from there in the past (a Sega Saturn 3D controller with a partially rusted connector).

Force feedback support is critical. Though I did just have a thought - I may have a free slot inside my computer which I could use to install a gameport card. Unfortunately I can't even find evidence that those exist, let alone what kind of slot they would need (as I'm not sure if my XPS has regular PCI slots on it).

That crazy port is called AD_Link; it's apparently for plugging in Creative's external "I/O console" device. Unfortunately, it doesn't look like it can in any way be adapted to a gameport.

There used to be such a thing as a dedicated gameport card, but I don't know if such a thing would be available for your system; someone smarter than me will have to determine that.

The easiest way to solve it would be to buy a used PCI soundcard with a gameport.

It seems those USB to gameport converters don't work with everything.

forcefeedback in xp is usb only