Brad, I just went and checked a box of parts, I'm holding a Yamaha YMF724A w/ the extra SPIDF out (in addition to the regular outputs) that you can have. PM me an address and I'll toss it in the mail.
It's a PCI card - YMF724E-V chip.
W98 drivers are still available:
http://www.yamahamultimedia.com/yec/...ard_Whelp.html