I finally decided to upgrade my 4 tuner Premier. Searched the forums, figured out which drive to get and purchased a WD20EURX from Amazon. After the drive arrived I dutifully followed the instructions using the rosswalker.co.uk/tivo_upgrade/ instructions. Drive copied fine. Drive expanded and supersized with no issues. Problems arose when I put the drive back into the Tivo - all the lights on the front of the Tivo flashed and it wouldn't boot. I put it back into my machine and JMFS is able to see the drive (and the fact that it's a Tivo drive), but I can't get the drive to boot in the Tivo. Further investigation revealed that it's an Advanced Format drive and I presume that's the issue (from what I've read), but haven't seen anywhere how to resolve the issue. Can someone point me in the direction of directions to setup and use an Advanced Format drive in my 4 tuner Premier? Many thanks in Advance.