it sounds to me like the card may have damaged USB components, or maybe there are some incompatibilities with your system, which is less likley. You can also check to see if you have all of the proper USB enabling extensions in your system folder. If you moved any extensions to the disabled folder or deleted them, you should move them back into the extensions folder and/or reinstall them from your OS 9 install disk. If your firewire/usb card came with software for the mac, you may need to install that, but it shouldn't be necessary if you have a proper 9.1 or later installation. Before sending the card in for a refund, make sure you have all of the proper software components in place (trying different configurations) and if it still doesn't work, send it back. Then get a MacAlly brand combo card. I have one and it works flawlessly, right out the box, no additional software (orangemicro makes goodfw/usb cards as well, I hear).
As far as the system profiler results you get, it only needs to detect the card and acknowledge the additional firewire and usb ports, not necessarily the devices attached to them (it will usually identify usb drives and some fw drives, but if doesn't i.d. them and they still work, there's nothing to worry about).