I found this on Sony's web site while looking for drivers.
# The drivers needed to connect most Sony® cameras and camcorders to a computer are already included in the Windows Vista and Windows XP operating systems. With these drivers, you should be able to connect and transfer files to a computer.
# The USB streaming feature is not supported with the Windows Vista operating system.
Looks like the driver should be built into Vista itself and if you are trying to stream content via USB, Vista doesn't support it. Have you tried any of the other audio/video outputs?