Since Vista SP1 Windows x64 requires drivers to be signed and you cannot permanently set testing mode. If reinstalling some other OS isn't an option I'd use VirtualBox and pass the USB devices through to either some linux distro or a 32bit windows guest OS.
I use VirtualBox a bit, I have never tried passing these devices though, does it really work ?
That's currently how I have my Blue Furies running, Win7 x64 Host, Ubuntu Server 13.10 guest, bfgminer 3.5.1.