Many users have experienced issues with FireWire devices not working with Win7-64. Often, those same devices worked with their previous OS, but not now. The cameras are not being recognized, or their other FW devices are just not being seen.
This appears to be related to the FW driver that Win7-64 installs by default, at least in most cases.
The "fix" is to go to Device Management, and locate the driver used for FireWire. One would replace that default driver with the one with the word "Legacy" in its name. Fairly simple to do, and it fixes FW issues for most users.
Not sure which driver will be the default, when Win7-64 gets the SP-1 (upcoming) update, and I only hope that if it is not the Legacy one, that will remain the option to fix things.
From the PrPro CS5 Forum, here are Colin Brougham's steps for resetting the FW driver:
I made that change.I now can control
the camcorder but I have no video
or audio in the capture screen.
Those issues are better handled in your original thread. Obviously in your case, it was not a matter of the Legacy FW driver, but something else entirely.