Well...not being inclined to leave well enough alone, I have some more bad suggestions for you.
(although, they're only "bad" because I don't know how to do them myself, I've just seen others write about doing them... and because you've probably already figured these things out on your own, since you can read and already know how to google and stuff...
but anyway...)
I see from these
NewEgg reviews that others have also had your problem, and that the drivers for the card are supposedly pre-loaded in Panther. Looks like
OWC used to sell this card, and their description on that Wayback capture also says the card was "plug & play"... soooooooo........
How about using that Pacifist app to locate and duplicate whatever kexts in Panther support the card; then use some of that black magic
like they're doing in that other forum to make Snow Leopard more PPC-friendly, and put the Panther kexts in Tiger/Leopard? Maybe it'll work?
Too much? Yeah me too. I'd probably just put the card on eBay, have a beer and call it a day.