(this is for 2k since I don't have a 9x box nearby, but I think it's the same)
run regedit
go to HKLM\SYSTEM\CurrentControlSet\Enum\PCI
in this key are all the PCI devices attached to your machine.
There should be several keys in there that say VEN_XXXX&DEV_YYYY(ignore the rest)
Those are the vendor and device ids for each device. If you expand each of those keys you'll get a big ugly string (like 2&ebb567f&0&48) If you click on that key you'll get the device info on your right-hand screen. What you're looking for is the DeviceDesc value. All of the devices that are properly installed (have drivers loaded) you'll see a proper name.
What you're looking for now is a key that says "unknown device" for it's DeviceDesc value. Go down the list of VEN/DEV keys and once you find the one that's unknown you've found the device. Now write down the hex code for vendor and device ids. (VEN_8086 = Intel)
Now go to "
http://www.yourvote.com/pci/" and search by vendor id. You can also see the device ids from there, but you should know by now what the device is. Go to the vendor's website, get the driver for 9x and
BOOYAH, GRANMA.... you're in biznis.
(Gimme a hard one next time)