Open the registry key:
You'll see subkeys like "VEN_1013&DEV_6003&SUBSYS_01531014&REV_01". That's a PCI identification string. Open these up and you'll see subkeys like "3&61aaa01&0&28". When you highlight one of these subkeys you'll see some values w/ description information. Look for the "Unknown" device.
Once you find the unknown device, search the "VEN_xxxx" and "DEV_xxxx" portion on Google, and you're likely to find something. Some of the Linux PCI code has a nice manifest of devices in it.
http://www.pcidatabase.com can help you search by vendor number, as well.
That's probably your best bet, short of opening the case, to find more about the device.