Are you looking for a very robust storage solution for your home network all I can say is once you see the video on Drobo your going to want one of these units.
With the capability to hold 4 Sata 1 or Sata 2 drives of various sizes the storage can grow as you need it and if a drive goes bad you just swap it out with the unit still online. It would take me 30 minutes to go over the feature set but I can tell you this unit is going to be very popular.
The price of the unit is somewhat of a barrier at $499.00 but once you see the full capabilities your going to see that it is worth the price. Drobo