We have released new WIN32 and WIN64 USB 2.0 Loopback device drivers today, V6.1 build 0001, that support Windows Vista.
These drivers are digitally signed and hence can be installed in 64-bit Vista. Also, under Windows Vista, the device driver is automatically installed for the 2nd and subsequent USB 2.0 Loopback plugs added to a system - like Windows 2000. This is unlike Windows XP/2003 where each device required manual installation via the Windows wizard.
Regards,
Ian (PassMark)