Looks like any Firewire 800 devices will function at the slower rate of 100Mbit/s if you install Windows XP SP2, according to a story here.
However, all is not lost. If you reinstall the SP1 Firewire drivers again, all will be well again.
La Cie have already released drivers that will combat the problem for their products, including the D2, the D2 Extreme, the D2 Triple Interface, the D2 Big Disk, the D2 Big Disk Extreme, the D2 Big Disk Triple Interface, the D2 Bigger Disk Triple Interface.