Topfield have made a Vista driver for the TF5000PVRt (and TF6000PVRt) range of PVR's. This driver only works for 32-bit versions of Vista, and also for 32-bit versions of Windows 7. Topfield have not (and from our understanding will not) release a driver for the 64-bit versions of Vista or Windows 7.
Updated drivers and updated software packages are available at:
Note: If you use an Icebox or IceBox2 to update the guide on the Topfield it doesn't matter what operating system you are running on your computer. This only applies if you are connecting your computer via a USB cable to the Topfield.