If you get a Series 1 DirecTivo, you can use your existing Turbonet and grab shows off it.

Series 2 does not have the edge connector that is present on the Series 1 motherboards. Instead, it has 2 USB ports on the back. You can use an USB ethernet adapter to grab guide updates and software updates, but I don't think there has been any luck ripping shows off a Series 2 yet.

With that said, DirecTivo is much better than DirecTV receiver + TiVo. Dual tuner is a killer app.