I am really confused.
The Tivo user guide says it can record about 400 hours of SD and 100 hours of HD.
http://www.virginmedia.com/tivo/tivo_quick_guide.pdf
Assuming SD is 2:1 like V+ (160gb = 80 hours) then I would calculate 1TB as 500 hours
I'm baffled! (dosen't take much)