Turbonet is based on 100Mb/sec Ethernet, but like all things what you actually get out of it is a lot lower than 100Mbits
Actual testing done by the guy who built the Turbonet shows the Tivonet board runs at about 900 kbits/sec in normal use.
Turbonet runs at 28 Mbits/sec when the tivo is receiving, but a lot lower than that when sending to the network (measured at about 9Mbits/sec) due to a bug with the Tivo transmit packet size (its stuck at a low value regardless of what the other end sends).
The turbonet card is supposed to be able to connect to a directTivo due to its small size.
i have 3 turbonet boards in my hand right now, I am not putting one into my Tivo right for two reasons.
1. I don't have the drivers for the board
2. My Tivo is busy tonight recording some TV so Turbonet has to wait for that event to finish (pluis the drivers to arrive).