First thing is trying with the external HD on and running before startup to see if that makes a difference. If not, then try plugging and unplugging the FW cord at the computer when the machine is fully booted. Give it at least 30 seconds, sometimes it is slow to show on the desktop. Check in the system profiler to see if it recognizes the PCI card, the firewire bus or the drive. It may not even though it is there, but if it does you are one step in the right direction.
Try putting the combo card in different PCI slots. The first slot in the 9600 is the recommended one but I had a problem with that slot and moved down, slot by slot til I found one that worked.
I also had a combo card which just plain did not work for Firewire but was fine for USB. I gave up on it and put in a separate xlr8 MachFire card and both external FW drives are recognized and work fine. I just use the combo card for USB now, with hub attached.
Is the La Cie drive externally powered? Is the combo card connected internally to the power supply or does it just get power from the PCI bus? This may make a difference but most 9600's have enough power to run small drives through the bus.
I also remember reading something recently about the FW cables being blamed for faulty drives. They recommend the shortest and heaviest cables. I think La Cie in particular had this problem.
Lastly, be sure once you mount the FW volume to the desktop, dismount it by dragging the icon to trash to avoid loss of data. Don't power down the FW drive until you unmount it or shutdown your Mac.