What's the chipset? You might want to dig a bit deeper, it's very possible that the chipset is supported, but that auto-detection fails. Back then a lot of those chipsets were very non-standard and you had to manually enter in IRQs and so forth.
I once had a sound card that wouldn't work right in Linux unless I booted to Win98 first, let it initialize the hardware, then WARM-boot the PC to Linux, where the driver was able to work with it fine. It may well have been an auto-detection/Plug-n-Pray issue.