Bit of a guess as never plugged hard drives into a tv but: freeview boxes tend to be first in the chain before the signal passes to the tv so the double tuner should allow you to record one channel and pass a second to the tv. I'm unsure how your present system works but if it runs from the analogue aerial input and you swop it to the freeview box digital input I suspect it may no longer be able to record something you are not watching, and so no longer add value. You may be able to sort out two analogue inputs but you'd need to experiment and may be better off adding the freeview to a different tv.