Theory says 5400 RPM is more than enough - and it is for general day to day - however it is nearly impossible to buy 5400 drives now.

Also when buying most of the 7200RPM drive you get an option of 8MB or 2MB cache - typically the 8MB have a 3 year warranty - definitely worth the extra $10 or so - as the drive is working 24 x7 and will almost certainly fail within the 3 years

Lastly if you start to do some of the more advanced functions the faster drives are definitely better.

I have two TIVO and have the Sanderton module for TIVO to TIVO transfers using MFS_FTP running.

I can watch a show previously recorded, have another one recording and have a third being loaded across the wire from another TIVO for later viewing - the system definitely starts to slow down at this point and the menus become sluggish - however when i had a 5400 RPM drive in my systems before they were unusable

Craig