I am running Windows XP on a PC with a FireWire S800 port, but my FireWire interface is not detected. How can I resolve this?

S800 ports suffer a performance decrease after installing SP2. This issue is known to affect XP running under Boot Camp on Apple hardware.

You can resolve this by applying Microsoft Hotfix KB885222

If you upgrade to Service Pack 3 after installing Hotfix KB855222, you may also need to apply Microsoft Hotfix KB955408