From what I can see, there are no 64-bit drivers. Instead, I installed a copy of 32-bit Vista on my second hard drive and I'm dual-booting, just so I can capture on my HTPC. That works.
VMWare server 2.0 would also theoretically work, but I haven't tried that - it works with USB devices, but I'm not sure if a Firewire device would work in the virtual window.
I've also tried on Windows 7 RC 64-bit, but that doesn't work either...
I keep checking every couple of months, but nothing yet.