I had been facing the same problem for last 6 months but yesterdsy when I installed Windows 7, it was having some problems with Firewire Add on card. I pulled it from one PCI slot and placed in the third slot and switched on the system.
It not only successfully installed Firewire Card but also detected my HC 96.

So finally I m satisfied.

Try doing the same if u have an add-on firewire card.

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a.malik